A.I. Explanation:

Correct answer: produced

Explanation: The word 'produced' is the past participle form of the verb 'produce,' which fits grammatically as it describes the greenhouse gas emissions that are generated by vehicles. This aligns with the context of discussing emissions in relation to photosynthesis.

Meaning: 'Produced' means to have created or generated something, in this case, greenhouse gas emissions.

Wrong options:

• add: 'Add' is a verb that means to join or combine, which does not fit the context of emissions being generated.
• pop: 'Pop' is a verb that typically refers to a sudden burst or sound, which is irrelevant in the context of emissions.
• transported: 'Transported' is the past participle of 'transport,' meaning to carry something from one place to another, which does not apply to the generation of emissions.
• tackle: 'Tackle' is a verb meaning to confront or deal with a problem, which does not fit as it does not describe the action of emissions being created.
• estimate: 'Estimate' is a verb that means to roughly calculate or judge the value, which does not relate to the production of emissions.

Correct answer: tackle

Explanation: The word 'tackle' is a verb that means to confront or deal with a problem, which fits contextually as it describes the efforts cities are making to address their emissions.

Meaning: 'Tackle' means to confront or take action to solve a problem.

Wrong options:

• add: 'Add' does not fit as it implies increasing something rather than addressing or solving an issue.
• pop: 'Pop' is unrelated to the context of addressing emissions and does not convey the intended meaning of action.
• produced: 'Produced' is a past participle that does not fit as it does not relate to the action of addressing emissions.
• estimate: 'Estimate' means to roughly calculate, which does not convey the action of dealing with emissions.
• transported: 'Transported' refers to carrying something, which is not relevant to the context of addressing emissions.

Correct answer: add

Explanation: The word 'add' is a verb that means to increase or contribute to something, which fits grammatically and contextually as it describes how trees and lawns contribute to the carbon-absorbing effect.

Meaning: 'Add' means to contribute or increase something.

Wrong options:

• pop: 'Pop' does not fit in this context as it does not relate to the contribution of trees and lawns to carbon absorption.
• produced: 'Produced' does not fit as it refers to creation rather than contribution in this context.
• tackle: 'Tackle' is about addressing a problem, which does not apply to the action of contributing to an effect.
• estimate: 'Estimate' means to calculate roughly, which does not relate to the action of contributing to an effect.
• transported: 'Transported' refers to carrying something, which is not relevant to the context of contributing to carbon absorption.