The police officers ___the suspicious killing of a diplomat before a renowned businessman __

The police officers ___the suspicious killing of a diplomat before a renowned businessman ___a couple of days ago ,

A had been investigating /was killed

B were investigating /had been killed

C have been investigating /was killed

D were investigated/killed

Correct Answer: Option A

এক্ষেত্রে বাক্য গঠনের সঠিক নিয়ম হল past perfect continuous +before +past indefinite .আবার ,past indefinite tense +after +past perfect +continuous.