Assume Your Company Produces Good X Using Only Two Inputs,capital

Multiple Choice

Assume your company produces good X using only two inputs,capital (K) and labor (L) .Also,assume L is measured on the vertical axis and K on the horizontal one.If the prices of inputs are P_K = $30 and P_L = 15,and your company is behaving efficiently,what is the slope of the isoquant at the current input mix?

A) -2
B) -1/2
C) 2
D) 1/2