The Following Inference Is an Application of Which Rule? ~(X)~(y) $\exists$

Multiple Choice

The following inference is an application of which rule? ~(x) ~(y) ( $\exists$ z) Rxyz.Therefore, ( $\exists$ x) (y) ( $\exists$ z) Rxyz.

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