The Following Argument Is an Instance of One of the Five

Multiple Choice

The following argument is an instance of one of the five inference forms Simp, Conj, Add, CD, DD.Identify the form. $\frac { [ ( X \cdot A ) \supset ( E \equiv M ) ] \cdot S } { ( X \cdot A ) \supset ( E \equiv M ) }$

A) Simp
B) Conj
C) Add
D) CD
E) DD