Meaning: 'Planted' refers to the act of putting a seed or plant in the ground to grow.

Wrong options:

• stay: 'Stay' is a verb that means to remain in a place, which does not fit the context of describing the action taken on the clones.
• rented: 'Rented' is the past participle of 'rent,' which refers to leasing something, and does not apply to the context of planting trees.
• concentrations: 'Concentrations' is a noun that refers to the amount of something in a given area, which does not fit as an action related to the clones.
• ozone: 'Ozone' is a noun referring to a gas, which does not describe an action taken on the clones.

Correct answer: ozone

Explanation: The term 'ozone' is a noun that refers to a specific type of gas known for its effects on the environment. In this context, it is used to describe the damage caused to the trees, making it the correct choice.

Meaning: 'Ozone' is a gas that can be harmful to plants and is a significant pollutant in urban areas.

Wrong options:

• stay: 'Stay' is a verb that does not relate to the type of damage being discussed.
• planted: 'Planted' is a verb that refers to the action of putting something in the ground, which does not fit the context of describing damage.
• rented: 'Rented' is a verb that does not apply to the context of environmental damage.
• concentrations: 'Concentrations' refers to the amount of a substance in a given area, which does not directly describe the type of damage.
• blows: 'Blows' is a verb that refers to the action of moving air, which does not fit the context of damage.

Correct answer: concentrations

Explanation: The word 'concentrations' is a noun that refers to the levels or amounts of ozone present in the air. It fits grammatically and contextually as it describes the varying levels of ozone in urban environments.

Meaning: 'Concentrations' refers to the amount of a substance, in this case, ozone, present in a specific area.

Wrong options:

• stay: 'Stay' is a verb that does not relate to the measurement of ozone levels.
• ozone: 'Ozone' is a noun that refers to the gas itself, not the levels or amounts of it.
• planted: 'Planted' is a verb that does not fit the context of discussing ozone levels.
• rented: 'Rented' is a verb that does not apply to the context of measuring concentrations of a gas.
• blows: 'Blows' is a verb that does not relate to the concept of measuring amounts.

Correct answer: urban

Explanation: The term 'urban' is an adjective that describes something related to a city or town. In this context, it correctly identifies the source of pollution affecting rural trees, making it the appropriate choice.

Meaning: 'Urban' refers to anything related to a city or town, particularly in contrast to rural areas.

Wrong options:

• stay: 'Stay' is a verb that does not describe a type of pollution or its source.
• planted: 'Planted' is a verb that does not fit the context of describing pollution sources.
• rented: 'Rented' is a verb that does not apply to the context of pollution.
• concentrations: 'Concentrations' is a noun that refers to levels of a substance, which does not describe the type of pollution.
• ozone: 'Ozone' is a noun that refers to the gas itself, not the type of pollution.

Correct answer: blows

Explanation: The word 'blows' is the present tense form of the verb that describes the action of air movement. It fits grammatically and contextually as it indicates how pollution is carried into rural areas.

Meaning: 'Blows' refers to the action of air moving, which can carry pollutants from one area to another.

Wrong options:

• stay: 'Stay' is a verb that does not relate to the action of air movement or pollution.
• planted: 'Planted' is a verb that does not fit the context of describing how pollution is transported.
• rented: 'Rented' is a verb that does not apply to the context of air movement or pollution.
• concentrations: 'Concentrations' is a noun that does not describe an action related to pollution.
• ozone: 'Ozone' is a noun that refers to the gas itself, not the action of how it moves.