Which of the following is an example of heterogeneity of services? a. The packaging of the pizza that I ordered today had a very different design and was made of recyclable paper. b. The tire I bought at a Chicago service station came with a discount but lasted as long as another other tire. c. The surgical instruments that doctors use in a New York hospital are the same as those used by doctors in the Miami hospital where I was examined. d. The customer service agent who contacted me last week was more helpful than the one who contacted me today.