Suppose for a Particular Production Function, the Cost-Minimizing Levels of Labor

Multiple Choice

Suppose for a particular production function, the cost-minimizing levels of labor and capital are $L = \frac { Q } { 10 } \sqrt { \frac { r } { w } } K = \frac { Q } { 10 } \sqrt { \frac { w } { r } }$ . If $r = 5$ and $w = 20$ , what is the equation for long-run total cost?

A) $\frac { 2 Q } { 5 }$
B) $\frac { 2 Q } { 10 }$
C) $2 Q$
D) $4 Q$