The various consequences of(1)/ the decision taken by the (2)/ finance ministry was not foreseen by the bureaucrats. (3)/ No error (4)

Answer

3

Explanation

were will replace was because -
The various consequences ( Main Subject) is in Plural. Hence, the Verb will also be in Plural as a Verb agrees with its Subject in Number.
Singular Subject `rarr` Singular Verb (Main Verb + S) Plural Subject `rarr` Plural Verb (Main Verb without S)
Look at the examples given below:

tomatoes each summer.