这题为什么选B 不选A？

discard2

Nuclear fusion is the force that powers the sun , the stars and hydrogen bombs, (merging the nuclei of atoms rather than splitting them apart , as  nuclear reactors do.)
A.merging the nuclei of atoms rather than splitting them apart , as  nuclear reactors do
B.and merges the nuclei of atoms , unlike nuclear reactors that split them apart.

这题为什么选B 不选A？

thanks

discard2

pgclt,thank you la.