Question

The terrorists who _____ (arm) heavily were able to escape.

• A. was armed
• B. were armed
• C. are armed
• D. had been armed

Answer 1

The correct option is B were armed

Here, 'were armed' in simple past tense is correct because it is used to indicate an action already completed. Here, the terrorists, who 'were armed' heavily were able to escape.
'Was armed' is incorrect because 'terrorists' is plural and with plural, we use were, not was.
'Are armed' in present continuous is incorrect because it is used for an action going on as we speak.
'Had been armed' in past perfect continuous is incorrect because it is used to indicate an action in the past that began before a certain point in the past and continued up untill that time.