Answer:
option c :
If the 80 votes not cast were for McClellan, Lincoln still had the majority.
Explanation:
McClellan won the popular vote but not the electoral vote.
not true because he clearly lost both
Lincoln won the popular vote but not the electoral vote.
not true because he clearly won both
If the 80 votes not cast were for McClellan, McClellan would have had the majority.
not true because 21 + 80 is not larger than 212.
so process of elimination