The Total Revenue R Earned Per Day (In Dollars) from a Pet-Sitting

Multiple Choice

The total revenue R earned per day (in dollars) from a pet-sitting service is given by $R ( p ) = - 10 p ^ { 2 } + 120 p$
Where p is the price charged per pet (in dollars) .

Find the price that will yield a maximum revenue.

A) $7.00
B) $10.00
C) $8.00
D) $6.00
E) $9.00