Janice's Kennel and Pet Spa Is Located in Sydney

Janice's Kennel and Pet Spa is located in Sydney. The company employs three pet attendants, four pet groomers and two front office staff who book appointments and keep records. The spa provides a range of services for dogs and cats including boarding, grooming, and obedience training. The grooming area includes a small retail section that carries dog and cat food, pet supplies, and toys. Assume Janice's Kennel and Pet Spa is currently boarding ten pets. The cost of food to board one more pet is best described as a

A) Fixed cost
B) Marginal cost
C) Sunk cost
D) Mixed cost