OFFICIAL EXPLANATION:
The original sentence correctly uses the simple past tense
contributed to refer to an event that occurred in the past.
Furthermore, the original sentence correctly uses
such as to introduce examples of baritone singers who made a contribution to the popularization of the “crooning” style of singing.
Note that it is acceptable to place words between such and as (
such baritone singers as). In order to do this correctly, the intervening words (
baritone singers) must be the category to which the examples (
Crosby and Columbo) belong.
(A)
CORRECT. As explained above, this choice uses the proper verb tense and is idiomatically correct.
(B) The 1930s is a decade, so it is redundant to state
of the decade. Furthermore,
and also is redundant—and means the same thing as
also in this context.
(C)
The commencement of the 1930s began is redundant;
commencement and
began convey the same meaning. In addition, the word
like means similar to;
the phrase such as should be used to introduce examples.
(D)
The beginning of the 1930s commencement is redundant;
beginning and
commencement convey the same meaning. In addition, the choice incorrectly uses the past perfect
had contributed. The contributed action occurs after the beginning of the 1930s, not before;
past perfect is used to convey something that happened before something else.(E) The choice incorrectly uses the past perfect
had decided. The decided action occurs after the beginning of the 1930s, not before;
past perfect is used to convey something that happened before something else. The sentence clearly indicates that they decided to participate “not long after” the 1930s commenced, so past perfect is not appropriate to use.