The harvest of grapes in the local valleys decreased in 1990 for the third ... ...

Determine whether or not there is an error in the underlined portion of the sentence above. If there is no error, select answer choice "A".
(A) The harvest of grapes in the local valleys decreased in 1990 for the third straight year but were
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Press: Set B - Subject-Verb Agreement