Meaning: 'Wreaking' means to cause something, especially something harmful or damaging, to happen.

Wrong options:

• freaking: 'Freaking' is an informal term often used for emphasis but does not convey the same meaning of causing damage, making it unsuitable here.
• breaking: 'Breaking' implies causing something to separate into pieces, which does not accurately describe the impact of microplastics on ecosystems as 'wreaking' does.
• creaking: 'Creaking' refers to a sound made by something moving slowly or under pressure, which is irrelevant in this context.

Correct answer: rid

Explanation: The verb 'rid' is appropriate here as it means to remove or free from something undesirable. The sentence context indicates that scientists are trying to eliminate microplastics from the planet, making 'rid' the correct choice.

Meaning: 'Rid' means to remove or eliminate something unwanted or undesirable.

Wrong options:

• study: 'Study' means to examine or investigate, which does not fit the context of removing microplastics from the environment.
• dominate: 'Dominate' implies control or superiority, which does not align with the action of removing microplastics.
• surround: 'Surround' means to encircle or enclose, which is not relevant to the action of eliminating microplastics.

Correct answer: respectively

Explanation: The word 'respectively' is used to indicate that the two percentages (98% and 99%) correspond to the two items mentioned (salt and microplastics). This fits grammatically and contextually, as it clarifies the relationship between the figures and what they refer to.

Meaning: 'Respectively' means in the order given, indicating that the first figure corresponds to the first item and the second figure to the second item.

Wrong options:

• distributively: 'Distributively' refers to distribution in mathematics or logic, which does not apply to the context of percentages related to removal efficiency.
• interrogatively: 'Interrogatively' relates to questioning, which is irrelevant in this context where we are discussing efficiency rates.
• retrospectively: 'Retrospectively' means looking back at past events, which does not fit the context of current efficiency rates.

Correct answer: smoothly

Explanation: The adverb 'smoothly' fits well as it describes how the method will work, indicating that it will operate without problems or difficulties. This aligns with the overall positive tone of the sentence regarding the effectiveness of the method.

Meaning: 'Smoothly' means in a smooth manner, indicating that the process will be efficient and without issues.

Wrong options:

• monthly: 'Monthly' refers to something occurring every month, which does not relate to the manner in which the method will work.
• unearthly: 'Unearthly' suggests something supernatural or otherworldly, which is not relevant to the context of a practical method.
• earthly: 'Earthly' refers to something related to the earth or mundane, which does not convey the intended meaning of efficiency in operation.