Explanation

Creating a filter: We read the prompt, and it doesn't appear to fail the universal tests. So, we proceed to the answer choices, scanning starting with (B), to eliminate exhaustively.

Finding objective defects: upon a scan, the answer choices reveal that we are dealing with a question of how to begin this sentence. Choices (B) and (C) are hardly tempting; we have simpler ways to describe the conditional meaning of the sentence - either "if" or "when."

That leaves us with (D), (E), and maybe (A). "If" and "when" both sound natural; which is correct? Precisely, "if" describes a condition, and "when" describes a time. We are talking more about a conditional relationship here in the sentence that the imaginary author is attempting to compose. It's more about the conditions under which a weight-lifting regimen occurs and less about specific time periods within that regimen. On those grounds, we eliminate choice (A).

Choices (D) and (E) are identical apart from the placement of "appropriate." What is really "appropriate" here, the augmentation or the increase in protein intake? The intended meaning is that, if you lift a ton and don't increase protein a ton, that's bad. If you lift only a little, the protein intake need only be a little. It's augmented either way; what must be "appropriate" is the level of increase of protein. Therefore, "appropriate" goes near "protein," since modifiers should be placed as near as possible to the words they modify. The correct answer is (E).