Were is right because of ago.Choose the correct answer
A few years ago, industrial gas emissions…. strictly regulated.
(A) were
(B) have been
(C) would be
(D) will be
Justification: the tense is not important with present perfect
Is my reasoning true?
ago is always with the simple past or it can not be used with the present perfect?
***not a teacher***
You may see that used with a present perfect. However, it refers to a simple activity finished in the past.
"I've known her since three years ago."
not a teacher
The activity started in the past and continues to the present. Thus, the present prefect tense is used.