which synchronizer mentioned below does not exist?\na) triple synchronizer\nb) dual synchronizer\nc) single…

Brief Explanations:

In the context of synchronizers, terms like dual (two - part), single (one - part) are common. "Double" is a synonym for "dual" in this context. However, "triple synchronizer" is not a standard or commonly - known type of synchronizer in relevant technical fields.

Answer:

A. Triple synchronizer