Subject verb agreement error and also tense errors.

The number should be followed by a singular verb.

is the answer E ??

IMO E
In Scotland, the number of wild salmon have been reduced because of uncontrolled deepsea and costal netting, by pollution, and by various other threats to the fish's habitat.

A. number of wild salmon have been reduced because of uncontrolled deep-sea and coastal netting (Not parallel to "by pollution" and "by various other threats")

B. number of wild salmon is reduced because deep-sea and coastal netting is not controlled (Not parallel to "by pollution" and "by various other threats")

C. numbers of wild salmon has been reduced because of uncontrolled deep-sea and coastal netting (Not parallel to "by pollution" and "by various other threats")

D. wild salmon's numbers are reduced by deep-sea and coastal netting that is not controlled (that is not controlled is wordy and makes it unparallel to "by pollution" and "by various other threats")

E. wild salmon's numbers have been reduced by uncontrolled deep-sea and coastal netting (parallel to "by pollution" and "by various other threats")

Please underline the sentence before posting.It takes few extra seconds to spot the underlined portion and thus time taken to find the answer is not true representative of actual time it would take on test.Thanks!

The OA is E