why the Civil War was triggered

[rachelhong2012]

Though research remains to be done into the reasons why the Civil War was triggered, scholars do not regard slavery to be the sole cause.


A) Though research remains to be done into the reasons why the Civil War was triggered, scholars do not regard slavery to be the sole cause.

B) Though research remains to be done into what triggered the Civil War, scholars do not regard slavery as the sole cause.

C) Though the reasons that triggered the Civil War remain to be researched, slavery is not regarded by scholars to be the sole cause.

D) Despite research remaining into the reasons why the Civil War was triggered, scholars do not regard slavery as the sole cause.

E) Scholars do not regard slavery as the sole cause of the Civil War, though the reasons for it being triggered remain to be researched.


***
I chose C, and it's wrong because:

(C) This choice incorrectly uses the unidiomatic "slavery is not regarded . . . to be the sole cause." Also, the main clause has been rewritten in the passive voice unnecessarily.



I also wonder if: "reasons that triggered the Civil War" is not logical? In other words, can we say reasons trigger an event?

Thanks!

[tim]

Exactly. Reasons don’t trigger events..

[gibran274]

is it B?

[tim]

yes