Answer:
The correct answer seems to be letter c. clearly given with no strings attached.
Explanation:
A gift is something voluntarily and willingly given to someone without any expectations of reciprocity, without payment, nor strings attached. On the other hand, a gratuity is a sort of payment. It is something you give to someone as a reward or payment for a service they have done for you. A tip you give to a waitress is a gratuity, not a gift. The present you give someone for their birthday is a gift, not a gratuity.