[单选题]
A nuclear reaction is saidnvnunl b,( -m0nr bjrul;k*r 75x*y ;s to be endothermic if the total kinetic ml h*5hjr qe t0d;.vg+,y wgn;energy is
A. less after the reaction than before.
B. equal both before and after the reaction.
C. greater after the reaction than before.
D. zero after the reaction.
