A Manager of a Firm with Market Power Faces the Marginal

A manager of a firm with market power faces the marginal revenue product and average revenue product curves shown below.The firm incurs weekly fixed costs of $1,800.The firm employs a single variable input,labor,which costs $600 per worker each week. Given the above,the 14^th worker hired adds $_______ to the firm's total revenue each week.

A) $200 per week
B) $400 per week
C) $500 per week
D) $700 per week
E) $900 per week