Peter's pizza place generates a monthly revenue of $12000. Throughout the month Peter spends $2400 on flour, $500 on tomatoes, $1500 on salami & spices, $800 on oil, and employs his sister whom he pays $3000. Calculate the value of the monthly output produced by Peter's pizza place using the value added method.

a. $6800
b. $12000
c. $6700
d. $3000
e. $3700