A firm's total cost is C(q)=100+5q2C(q) = 100 + 5q^2C(q)=100+5q2. The average cost AC(q)AC(q)AC(q) is minimized when:
MC=ACMC = ACMC=AC
MC=0MC = 0MC=0
AC=0AC = 0AC=0
MC=100MC = 100MC=100