The Estimated Monthly Sales of Mona Lisa Paint-By-Number Sets Is $q = 120 e ^ { p - \frac { 5 p ^ { 2 } } { 2 } }$

Multiple Choice

The estimated monthly sales of Mona Lisa paint-by-number sets is given by the formula $q = 120 e ^ { p - \frac { 5 p ^ { 2 } } { 2 } }$
Where q is the demand in monthly sales and p is the retail price in yen. At what price will revenue be a maximum Round the answer to the nearest hundredth.

A) 66.99 yen
B) 0.56 yen
C) 0.78 yen
D) 0.99 yen
E) 1.22 yen