The Interaction $\pi$ ^- + P $\rightarrow$ $\pi$ ^- + ⁺ Violates the Principle of Conservation

The interaction $\pi$ ^- + p $\rightarrow$ $\pi$ ^- + ⁺ violates the principle of conservation of:

A) baryon number
B) lepton number
C) strangeness
D) angular momentum
E) none of these