Meaning: 'Adjusts' means to change or modify something to achieve a desired fit or function, in this case, the lens changing its shape to focus light properly.

Wrong options:

• shows: The verb 'shows' implies displaying something, which does not fit the context of changing shape; it lacks the necessary action of modification.
• selects: The verb 'selects' suggests choosing from options, which is not relevant to the lens's function of focusing light.
• presents: The verb 'presents' indicates showing or displaying, which does not convey the action of changing shape necessary for focusing light.

Correct answer: to ensure

Explanation: The phrase 'to ensure' is an infinitive form that indicates purpose, fitting grammatically after a comma and explaining the reason for the lens's action. Contextually, it clarifies that the lens's adjustment is aimed at providing a clear image.

Meaning: 'To ensure' means to make certain that something happens, in this case, guaranteeing a clear image for the viewer.

Wrong options:

• ensures: The verb 'ensures' is in the present tense and does not fit grammatically after a comma in this context, as it lacks the purpose indication required here.
• ensured: This option is repeated and is incorrect for the same reasons as above.

Correct answer: far away

Explanation: The phrase 'far away' is an adverbial expression that describes distance, fitting grammatically and contextually to indicate the range of vision. It aligns with the idea of seeing objects at varying distances, complementing 'short distances.'

Meaning: 'Far away' means at a great distance, indicating the lens's ability to focus on objects that are not close by.

Wrong options:

• in between: The phrase 'in between' suggests a middle distance, which does not align with the context of seeing both near and far objects.
• further apart: The phrase 'further apart' implies separation rather than distance from the viewer, which does not fit the context of vision.
• all along: The phrase 'all along' suggests continuity over time, which is irrelevant to the context of distance in vision.

Correct answer: consists

Explanation: The verb 'consists' is in the present tense and correctly indicates what the lens is made of, fitting grammatically with the subject 'lens.' Contextually, it describes the composition of the lens, which is essential for understanding its properties.

Meaning: 'Consists' means to be made up of or composed of certain elements, in this case, water and protein that make up the lens.

Wrong options:

• constitutes: The verb 'constitutes' implies forming or making up something but is less commonly used in this context compared to 'consists.'
• comprises: The verb 'comprises' suggests inclusion but is often used in a different grammatical structure, making it less suitable here.
• composes: The verb 'composes' implies creating or forming, which does not accurately describe the relationship of the lens to its components.