A Short-Run Production Function Was Estimated As $Q = - 0.002 L ^ { 3 } + 0.16 L ^ { 2 }$

Multiple Choice

A short-run production function was estimated as $Q = - 0.002 L ^ { 3 } + 0.16 L ^ { 2 }$ At 20 units of labor,what is marginal product?

A) 6.0
B) 1.9
C) 6.3
D) 4.0
E) 2.4