A smartphone manufacturer produces a highly innovative smart phone. The smart phone is so popular that customers pay for the smart phone on average 10 days in advance to the delivery. The time span from starting the production until the phone is delivered to the customers is on average 50 days. The smart phone manufacturer pays their suppliers on average 50 days after receiving the raw material. What is the Cash Conversion Cycle of the car manufacturer?

a. 10 days

b. 110 days

c. -10 days

d. none of the above answers