Contrast keywords are fairly common on GMAT Sentence Correction questions. Some of the most common words you’ll see include:

• but
• however
• on the other hand
• unlike
• in contrast to
• different from
• whereas
• while
• yet
• as opposed to

Let’s look at an example question now

However a minimal role in causing air pollution, trash pollutes both land and sea, creates problems in wildlife habitats, and harms endangered species

A) However
B) With
C) Being
D) Therefore accounting for
E ) Despite playing

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Here we have the phrases “minimal role” and “trash pollutes..creates problems…harms…” which tells us we’ll need a Contrast word to open the sentence. (B), (C), and (D) do not provide a contrast, so we can quickly eliminate them.

Between (A) and (E), (E) is the better choice since “However a minimal role…” is an awkward construction. A better way to use “however” here would be: However minimal its role….