Answer: B) not rewarded for hard work.
Unrequited refers to something that is not returned or reciprocated. It is often used in the context of love, to describe a situation in which a person loves someone who does not love him back.
Toil refers to extremely difficult and exhausting labour, often physical.
"Unrequited toil" most likely refers to very hard, tiring work for which the person does not gain anything in return.
