Ross 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. ross is
a. ​required to pay because sara obtained a degree at tech.
b. ​required to pay because a job can be hard to find after college.
c. ​not required to pay because sara was already at tech.
d. ​not required to pay because obtaining a degree benefits sara.