I need help with question 5. How do I solve it?

4) In the short-run, marginal cost is increasing when a. Mpl is decreasing b. Apl is decreasing c. Apl is increasing d. Mpl is increasing 5) suppose a firm has the following total cost function: Tc= 50+2q^2. What is the minimum price necessary for the firm to earn profit ? a. p= $35 b. p=$20 C. p=$30 d. p=$40 6) suppose the total cost of producing t-shirts can be represented as Tc= 50+2q. The marginal cost of the 5th t-shirts is a. 2