Sam's Scarves Has 2 Knitting Machines and Employs 2 People

Sam's Scarves has 2 knitting machines and employs 2 people. They produce 15 scarves a day. If the firm hires an additional person, the 3 workers can produce 19 scarves a day other things remaining the same. The market for scarves is perfectly competitive and the price of a scarf is $20. The value of marginal product of the third worker is

A) $80.
B) $300.
C) $380.
D) 4 scarves.