Meaning: 'Identified' means to recognize or establish the existence of something.

Wrong options:

• advertised: 'Advertised' is the past tense of 'advertise,' which means to promote or publicize something, and does not fit the context of scientific discovery.
• adopted: 'Adopted' is the past tense of 'adopt,' which means to take up or accept something, but it does not relate to the action of discovering a hole in the ozone layer.
• isolated: 'Isolated' is the past tense of 'isolate,' meaning to separate from others, which does not apply to the context of identifying a hole.
• accorded: 'Accorded' is the past tense of 'accord,' meaning to grant or give, which does not fit the context of scientific identification.

Correct answer: adopted

Explanation: The term 'adopted' is the past tense of 'adopt,' which fits grammatically as it describes the action taken by countries in the past to accept the Montreal Protocol. This aligns with the context of international cooperation to address environmental issues.

Meaning: 'Adopted' means to formally accept or implement a policy or agreement.

Wrong options:

• identified: 'Identified' does not fit here as it refers to recognizing something, not the action of countries taking up an agreement.
• advertised: 'Advertised' is unrelated to the context of countries accepting an agreement; it refers to promoting something.
• isolated: 'Isolated' means to separate, which does not apply to the context of countries coming together to accept an agreement.
• accorded: 'Accorded' means to grant or give, which does not fit the context of countries formally accepting a global agreement.

Correct answer: tied

Explanation: The word 'tied' is the past participle of 'tie,' which fits grammatically as it describes the relationship between the synthetic chemicals and the destruction of the ozone layer. It is contextually appropriate as it indicates that these chemicals are linked to the problem.

Meaning: 'Tied' means to be connected or linked to something.

Wrong options:

• advertised: 'Advertised' does not fit as it refers to promoting something, which is unrelated to the context of chemical impact on the ozone layer.
• adopted: 'Adopted' does not fit here as it refers to accepting an agreement, not describing the relationship of chemicals to ozone destruction.
• isolated: 'Isolated' means to separate, which contradicts the idea of being linked to the destruction of the ozone layer.
• accorded: 'Accorded' means to grant or give, which does not relate to the connection between chemicals and ozone layer destruction.