A Local Veterinary Clinic Recently Had 25 Horses Admitted from the Same

A local veterinary clinic recently had 25 horses admitted from the same barn. It was determined that most cases of West Nile virus infection in the group of 25 horses were caused by infection by another horse. In this case, modeling the number of cases diagnosed with a binomial distribution is not appropriate because:

A) the success on different trials needs to be mutually exclusive and this is not the case here.
B) the success on individual trials needs to be independent.
C) the success on individual trials needs to be positive.
D) n = 25 is a very small sample.