The answer would be either magnifying clues or fleshing reactions.
(2 or 4)
A should be the right answer
The correct answer among the choices provided is the third option. Two independent clauses incorrectly joined are referred to as a fused sentence. A fused sentence is also called a run-on sentence. To correct this, an appropriate conjunction or punctuation mark must be put in between the clauses.
Plethora would be the collective noun because it is a group.
