sa18 wrote:
Can someone please explain why is B incorrect?
I think B is wrong because of its tense.The situation stated in the question has started long ago and is still in continuation and has not ended yet.Hence the tense (Present perfect progressive) Has Been is perfectly suitable.
Please correct me if I am wrong.
/english-betterindia/media/post_attachments/uploads/2023/03/biogas-unit-installation-1679901883.jpg)
