Every Year, the Veterinary Hospital at a Major Research University

Multiple Choice

Every year, the veterinary hospital at a major research university treats a number of horses that have stones called enteroliths in their guts. A sample of 20 years shows that on average about 2% of horses presenting at the veterinary hospital are treated for enteroliths. Some breeds of horses seem more prone to developing enteroliths than others. Below is a table with the distribution of enteroliths among the breeds. The probability that a horse arriving at the veterinary hospital is not an Arabian or a quarter horse is:

A) 0.55.
B) 0.25.
C) 0.45.
D) 0.75.