When the price faced by a competitive firm was $5, the firm produced nothing in theshort

run. However, when the price rose to $10, the firm produced 100 tons of output. Fromthis

we can infer that:

a.the firm's marginal cost curve must be flat.

b.the firm's marginal costs of production never fall below$5.

c.the firm's total cost of producing 100 tons is less than$1000.

d.the"minimumprice" for this firm lies between $5 and $10.