Tom Tunes Pianos in His Spare Time for Extra Income

Tom tunes pianos in his spare time for extra income. Buyers of his service are willing to pay $155 per tuning. One particular week, Tom is willing to tune the first piano for $120, the second piano for $125, the third piano for $140, and the fourth piano for $160. Assume Tom is rational in deciding how many pianos to tune. His producer surplus is

A) $95.
B) $80.
C) $75.
D) $60.