Answer :
Atoms gain or lose electrons to
increase their stability. The answer is letter C. Remember noble gases? They
follow the octet rule in which their shells are electrons are filled with eight
electrons. So the atoms that do not belong to the noble gas tend to be
restless. They want their electrons to be filled to follow the octet rule. That
is why they tend to share or gain electrons. Suppose you have a compound of
CCl4. You know that chlorine can only share 1 electron because 7 of its
electrons are filled. Also, in carbon, it can only share 4 electrons because 4
of it are already filled. That is why carbon needs four chlorine to form CCl4.