Meaning: 'Skyscrapers' are tall, multi-story buildings typically found in urban areas.

Wrong options:

• residential: 'Residential' is an adjective that describes areas or buildings meant for living, which does not fit as a noun in this context.
• vegetables: 'Vegetables' is a noun referring to edible plants, which does not relate to the type of buildings being discussed.
• quality: 'Quality' is a noun that refers to the standard of something, which does not fit as it does not describe a type of building.
• popular: 'Popular' is an adjective that describes something widely liked or accepted, which does not fit as a noun in this context.
• biodiversity: 'Biodiversity' is a noun that refers to the variety of life in a particular habitat, which does not relate to buildings.
• tranquillity: 'Tranquillity' is a noun that refers to a state of calm, which does not fit as it does not describe a type of building.

Correct answer: vegetables

Explanation: The word 'vegetables' is a plural noun that fits grammatically and contextually as it refers to the edible plants that urban dwellers can grow in their gardens. It aligns with the theme of urban gardening and food sources.

Meaning: 'Vegetables' are edible plants or parts of plants, typically consumed as food.

Wrong options:

• residential: 'Residential' is an adjective that does not fit as it does not refer to a type of food or plant.
• quality: 'Quality' is a noun that refers to the standard of something, which does not relate to food or gardening.
• skyscrapers: 'Skyscrapers' refers to tall buildings and does not relate to the context of growing food.
• popular: 'Popular' is an adjective that describes something widely liked, which does not fit as it does not refer to food.
• biodiversity: 'Biodiversity' is a noun that refers to the variety of life, which does not fit as it does not refer to a type of food.
• tranquillity: 'Tranquillity' is a noun that refers to calmness, which does not relate to food.

Correct answer: popular

Explanation: The term 'popular' is an adjective that describes the increasing acceptance and widespread participation in community gardening projects. It fits grammatically as it modifies the noun 'projects' and aligns with the context of discussing trends in urban gardening.

Meaning: 'Popular' means well-liked or widely accepted by many people.

Wrong options:

• residential: 'Residential' is an adjective that describes living areas, which does not fit as it does not describe the nature of gardening projects.
• vegetables: 'Vegetables' is a noun that refers to edible plants, which does not fit as it does not describe the popularity of projects.
• quality: 'Quality' is a noun that refers to the standard of something, which does not fit as it does not describe the nature of gardening projects.
• skyscrapers: 'Skyscrapers' refers to tall buildings and does not relate to the popularity of gardening projects.
• biodiversity: 'Biodiversity' is a noun that refers to the variety of life, which does not fit as it does not describe the popularity of projects.
• tranquillity: 'Tranquillity' is a noun that refers to calmness, which does not relate to the popularity of gardening projects.

Correct answer: quality

Explanation: The word 'quality' is a noun that fits grammatically and contextually as it refers to the standard or condition of urban living, which is enhanced by green spaces. It aligns with the overall theme of improving urban environments through gardening.

Meaning: 'Quality' refers to the standard or degree of excellence of something, in this case, urban living.

Wrong options:

• residential: 'Residential' is an adjective that describes living areas, which does not fit as it does not refer to the standard of urban living.
• vegetables: 'Vegetables' is a noun that refers to edible plants, which does not relate to the quality of urban environments.
• popular: 'Popular' is an adjective that describes something well-liked, which does not fit as it does not refer to the standard of living.
• skyscrapers: 'Skyscrapers' refers to tall buildings and does not relate to the quality of urban living.
• biodiversity: 'Biodiversity' is a noun that refers to the variety of life, which does not fit as it does not refer to the standard of urban living.
• tranquillity: 'Tranquillity' is a noun that refers to calmness, which does not relate to the quality of urban living.