Rob promises to pay Sara, his niece, $5,000 if she obtains her degree at Tech University, where she is in her third year. Sara graduates. Rob is​ Select one:
a. ​required to pay because a job can be hard to find after college.
b. ​not required to pay because obtaining a degree benefits Sara.
c. ​required to pay because Sara obtained a degree at Tech.
d. ​not required to pay because Sara was already at Tech.