The Particle Reaction $\pi ^ { + } + \mathrm { p } \rightarrow \Sigma ^ { + } + \pi ^ { 0 }$

Multiple Choice

The particle reaction $\pi ^ { + } + \mathrm { p } \rightarrow \Sigma ^ { + } + \pi ^ { 0 }$ cannot occur because

A) electric charge is not conserved.
B) strangeness is not conserved.
C) baryon number is not conserved.
D) all of the above are not conserved.
E) both (a) and (b) above are not conserved.