JW Enterprises is considering a new marketing campaign that will require the addition of a new computer programmer and new software. The programme will occupy an office in JW's current building and will be paid $8,000 per month. The software license costs $1,000 per month. The rent for the building is $4,000 per month. JW's computer system is always on, so running the new software will not change the current monthly electric bill of $900. The incremental expenses for the new marketing campaign are:
a. $8,000 per month
b. $13,000 per month
c. $13,900 per month
d. $9,000 per month