A firm has fixed costs of $2,000. Its short-run production function isf(x)=4x^0.5, where x is the amount of the variable factor that it uses. The price of the variable factor is$4,000 per unit. If y is the amount of output produced, the firm's short-run total cost function is

8,000y.

4,000 + 250y².

4,000 + 4,000y.

(4,000/y) + 4,000.

2,000 + 250y².