The manner in which bombs exploded in five trains with in a short span of time suggests that it is a part of a ......

ANS:B - conspiracy

Sabotage:

Deliberately destroy, damage, or obstruct (something), especially for political or military advantage.

"power lines from South Africa were sabotaged by rebel forces".

Synonyms: wreck, deliberately damage, vandalize, destroy, obstruct, disrupt, cripple, impair, incapacitate More.