However scientists determine to measure the presence of frozen water

Right. The post is edited now.

The explained answer by Kaplan:

Read the Original Sentence Carefully, Looking for Errors:

From the initial read of the sentence, some students may suspect that "determine to measure…" is awkward. However, grammatically it is correct. As no errors jump out here, immediately proceed to step 2.

Scan and Group the Answer Choices:

A quick scan of the answer choices reveals a 3:2 split, making our first decision whether "However…" or "No matter how…" is appropriate. Technically, either one of them could work in the context of the sentence, so we are forced to look at each choice individually.

Eliminate Wrong Answer Choices:

Answer choice (B) is incorrect because it shifts to the less-preferred passive voice. It also adds the ambiguous pronoun "it" at the end of the choice, which makes the sentence illogical.

Answer choice (C) shifts the original verb "determine" to the adjective "determined" and uses it to describe the scientists, This shift changes the meaning of the sentence so we can eliminate this choice.

In answer choice (D), the verb phrase "are determining to measure" is less preferred to the original present tense "determine to measure".

Choice (E) introduces the awkward construction "how have scientists determined to measure" and is incorrect.

The original sentence is correct as it is given. Therefore, Answer Choice (A) is correct.

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