Meaning: 'Biodiversity' means the variety of different species of plants and animals in a particular area.

Wrong options:

• species: 'Species' is a noun that refers to a group of living organisms, but it does not fit as the object of the verb 'affecting' in this context.
• untreated: 'Untreated' is an adjective that describes something not processed or dealt with, which does not fit as a noun here.
• stagnation: 'Stagnation' is a noun that refers to a lack of activity or growth, which does not align with the context of human impact on coastal life.
• concern: 'Concern' is a noun that indicates worry or interest, but it does not fit the grammatical structure needed in this sentence.

Correct answer: unleashed

Explanation: The word 'unleashed' is the past participle of 'unleash,' functioning as an adjective that describes the waste water and solid waste. It fits grammatically and contextually, indicating that these wastes have been released into the environment.

Meaning: 'Unleashed' means released or set free, particularly in a way that causes harm or disruption.

Wrong options:

• species: 'Species' is a noun that does not fit grammatically as it cannot describe waste water and solid waste.
• untreated: 'Untreated' is an adjective that could describe waste but does not convey the action of being released, which is essential in this context.
• stagnation: 'Stagnation' is a noun that does not fit as it does not describe the state of waste water and solid waste.
• concern: 'Concern' is a noun that does not grammatically fit as it does not describe the waste.

Correct answer: contamination

Explanation: The term 'contamination' is a noun that refers to the presence of harmful substances in the water. It fits grammatically as the object of the verb 'cause' and contextually aligns with the negative effects of waste on water quality.

Meaning: 'Contamination' means the act of making something impure or harmful by adding a substance.

Wrong options:

• species: 'Species' is a noun that does not fit as it does not describe a harmful effect on water.
• untreated: 'Untreated' is an adjective that does not fit as it does not describe the result of waste in the water.
• stagnation: 'Stagnation' is a noun that refers to inactivity, which does not fit the context of harmful effects on water.
• concern: 'Concern' is a noun that indicates worry but does not describe a specific harmful effect.

Correct answer: species

Explanation: The word 'species' is a noun that refers to different kinds of organisms. It fits grammatically as the subject of the phrase 'invasive species' and contextually aligns with the discussion of organisms that disrupt local ecosystems.

Meaning: 'Species' refers to a group of living organisms that can interbreed.

Wrong options:

• biodiversity: 'Biodiversity' is a noun that refers to the variety of life, but it does not fit as it does not describe a specific group of organisms.
• untreated: 'Untreated' is an adjective that does not fit as it does not describe a type of organism.
• stagnation: 'Stagnation' is a noun that does not relate to organisms and does not fit in this context.
• contamination: 'Contamination' is a noun that refers to pollution, which does not describe a type of organism.