Answer:
a) Only hiring workers who have earned good grades in college.
Explanation:
The Marginal Productivity theory defines as change in revenue of a business resulting due to employment of one additional labor.
This theory has many assumptions that perfect competition prevails in the market. All workers have same abilities and skills. Productivity of labors can be measured accurately. Every unit is homogeneous etc.
To overcome this information problem a firm should hire only workers who have earn good grades in college. It assumes that these workers will have greater skills and will contribute in revenue contribution to the organization.