Which of the Answer Choices Below Could Be the Unknown $\mathrm {\bar{p}}$

Multiple Choice

Which of the answer choices below could be the unknown particle X in the following reaction? p + $\mathrm {\bar{p}}$ → $\pi^{+}$ + X

A) π⁰
B) π⁻
C) e⁺
D) p
E) $\mathrm {\bar{n}}$