Meaning: Producing means causing or giving rise to something, in this case, serious complications for marine wildlife.

Wrong options:

• encouraging: 'Encouraging' is an adjective that implies support or promotion, which does not fit the context of causing complications.
• nourishing: 'Nourishing' is an adjective that refers to providing sustenance, which is not relevant to the negative implications of plastic build-up.
• estimating: 'Estimating' is a verb that refers to making an approximation, which does not fit as it does not describe the action of causing complications.
• dominating: 'Dominating' is a verb that implies control or influence, which does not align with the context of complications arising from plastic.
• feeding: 'Feeding' is a gerund that implies consumption, which does not fit as it does not describe the action of causing complications.

Correct answer: estimating

Explanation: The term 'estimating' is a present participle that fits grammatically and contextually, as it describes the action of the studies making an approximation about the amount of plastic waste in the oceans.

Meaning: Estimating means making an approximate calculation or judgment about a quantity.

Wrong options:

• encouraging: 'Encouraging' does not fit as it implies support rather than making a calculation about plastic waste.
• nourishing: 'Nourishing' is irrelevant here as it refers to providing sustenance, not making estimates.
• producing: 'Producing' does not fit as it implies creation rather than estimation of quantities.
• dominating: 'Dominating' does not relate to the context of studies making calculations about plastic waste.
• feeding: 'Feeding' does not fit as it refers to consumption, not the action of estimating.

Correct answer: feeding

Explanation: The word 'feeding' serves as a gerund that fits grammatically and contextually, indicating the action of animals consuming plastic, which is a critical point in the discussion of marine wildlife and pollution.

Meaning: Feeding refers to the act of consuming food, in this case, mistakenly consuming plastic as if it were food.

Wrong options:

• encouraging: 'Encouraging' does not fit as it implies support rather than the act of consuming.
• nourishing: 'Nourishing' is irrelevant as it refers to providing sustenance, not the act of consuming harmful materials.
• estimating: 'Estimating' does not fit as it refers to making a calculation, not the act of consumption.
• dominating: 'Dominating' does not relate to the context of consumption and implies control rather than feeding.
• ingesting: 'Ingesting' is a synonym for feeding but does not fit grammatically in this context as it does not serve as a gerund.

Correct answer: ingesting

Explanation: The term 'ingesting' is a gerund that fits grammatically and contextually, indicating the action of consuming plastic, which leads to intestinal blockage and death.

Meaning: Ingesting means taking in food or substances through the mouth, in this case, referring to the consumption of plastic.

Wrong options:

• encouraging: 'Encouraging' does not fit as it implies support rather than the act of consuming.
• nourishing: 'Nourishing' is irrelevant as it refers to providing sustenance, not the act of consuming harmful materials.
• producing: 'Producing' does not fit as it implies creation rather than consumption.
• feeding: 'Feeding' is a synonym for ingesting but does not fit grammatically in this context as it does not serve as a gerund.
• dominating: 'Dominating' does not relate to the context of consumption and implies control rather than ingesting.