Which of the Following Is NOT a Characteristic of a Binomial

Which of the following is NOT a characteristic of a binomial ?

A) There are n identical trials, and all trials are independent.
B) Each trial has two possible outcomes, which are traditionally labelled "failure" and "success," and the probability of success p is the same on each trial.
C) We are interested in x, the number of successes observed during the n trials.
D) The probability of failure may differ from trial to trial.