The Following Inference Is an Application of Which Rule? (Mj $\equiv$

Multiple Choice

The following inference is an application of which rule? (Mj • Bj) $\equiv$ Dj.Therefore, ( $\exists$ x) [(Mx • Bj) $\equiv$ Dj].

A) quantifier negation
B) universal instantiation
C) existential generalization
D) existential instantiation
E) universal generalization