The correct option is A were taken
Here, 'were taken' in simple past tense is correct because it indicates an action already completed. Moreover, the whole passage is in past tense. Thus, 'were taken' is correct.
'Have been taken' in present perfect continuous is incorrect because it is used to indicate an action that started at some point in the past and may or may not be complete. The whole passage is in past tense.
'Were being taken' in past perfect continuous is incorrect because it is used to indicate an action in the past that begin before a certain point in the past and continued up untill that part of time.