An important reason to be vaccinated is because vaccination

OFFICIAL EXPLANATION




• OVERVIEW: redundancy

On the GMAT and in good writing generally, "the reason is" and "because" are redundant.
GMAC prefers concision. The reason is and because repeat the same idea.

The reason tells us why something happened.
Because also tells us why something happened.
-- The reason already announces that we are about to hear a causal explanation. Because indicates the same idea.
-- This site, here discusses the construction at issue. Essentially we are saying that "the reason is the reason.”
-- In speech, native speakers frequently use "the reason . . is because." They also use "the reason why." Both usages are redundant.
-- GMAC follows the typical rule for formal writing: because and the reason is are redundant, and concision is important.

• Split #1: An important reason . . . . is because = redundant

The word because means "for the reason that."
See Oxford online dictionary, here.

The correct usage is "An important reason to do XYZ is that" [it prevents the spread of disease].

GMAC tests this redundant and thus incorrect usage.
In fact, this phrasing and "reason why" are among the very few redundancies that prompt me to eliminate an answer on the first pass. (Otherwise, I leave redundancy until the end of analysis.)
Options A and B both deploy the incorrect phrasing.
Eliminate A and B.

• Split #2: an important reason . . . . is why = redundant

A reason is a "why."
This phrasing, too, is redundant, and it too is tested by GMAC.
Option D uses a reason why.
Eliminate D

• Split #3: Concision really is a thing.
Options C and E are both grammatical.
Option E is unnecessarily long.
Use concision at the end of analysis, as we are doing in this case.
Most of the time, if you can say the same thing in fewer words, you should do so or pick the answer that does so.
Eliminate option E.

The best answer is C.


COMMENTS

Gauravji21 and aditigupta1208 , welcome to SC Butler.
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