Kenny's Cartage Hauls Crushed Stone for $15 a Ton and Has

Multiple Choice

Kenny's Cartage hauls crushed stone for $15 a ton and has total costs given by TC = 100 + 5X + X².The profit-maximizing level of output is:

A) 5 tons.
B) 2.1 tons.
C) 10 tons.
D) 20 tons.
E) 0 tons.