Meaning: 'Awareness' refers to the knowledge or perception of a situation or fact, in this case, the issue of plastic pollution.

Wrong options:

• gnarls: The term 'gnarls' is a verb form that does not fit the context of public understanding; it means to growl or snarl, which is unrelated here.
• fin: 'Fin' is a noun referring to a limb of a fish or marine animal, which does not relate to the concept of public understanding or action.
• effect: 'Effect' is a noun that refers to a change that has occurred due to an action, but it does not fit grammatically as it would require a different structure in this context.

Correct answer: reaches

Explanation: The verb 'reaches' is appropriate here as it indicates the action of plastic waste arriving at the ocean, fitting grammatically in the present tense and contextually describing the movement of waste from coastal areas to the ocean.

Meaning: 'Reaches' means to arrive at or extend to a particular point, in this case, the ocean.

Wrong options:

• trust: 'Trust' is a noun or verb that implies reliance on someone or something, which does not fit the context of plastic waste movement.
• stays: 'Stays' suggests remaining in a place, which contradicts the intended meaning of plastic waste moving into the ocean.
• make: The verb 'make' does not fit grammatically or contextually, as it implies creation rather than movement.

Correct answer: bellies

Explanation: The noun 'bellies' fits grammatically as it refers to the stomachs of the marine creatures, which is contextually relevant to the discussion of their inability to consume real food due to plastic ingestion.

Meaning: 'Bellies' refers to the stomachs of animals, indicating where the plastic particles accumulate.

Wrong options:

• stares: 'Stares' is a verb that means to look fixedly, which does not relate to the physical condition of the animals' stomachs.
• great: 'Great' is an adjective that does not fit as it does not describe a physical part of the animals' bodies or their condition.
• speeds: 'Speeds' is a noun or verb related to quickness, which is irrelevant in the context of discussing the stomachs of marine creatures.

Correct answer: affect

Explanation: The verb 'affect' is correctly used here as it indicates the action of having an impact on human health and food security, fitting grammatically in the context of potential consequences.

Meaning: 'Affect' means to have an influence on or make a change to something, in this case, human health and food security.

Wrong options:

• matter: 'Matter' is a noun that refers to substance or material, which does not fit the context of influencing health or security.
• gets: The verb 'gets' implies obtaining or receiving, which does not convey the intended meaning of influencing or impacting.
• mouth: 'Mouth' is a noun that refers to the opening in the face, which is unrelated to the context of health and food security.