Letting $W$ Stand for the Set of Whole Numbers, I the Set

Multiple Choice

Letting $W$ stand for the set of whole numbers, I the set of integers, $I ^ { + }$ the set of positive integers, and $I ^ { - }$ the set of negative integers, perform the indicated operation.
-Find $\mathrm { I } ^ { + } \cup \mathrm { I } ^ { - }$

A) $\mathrm { I } ^ { + }$
B) $W$
C) $I - \{ 0 \}$
D) I