Which of the following is a discrete random variable?

If you flip a biased coin, which has a chance of being heads and of being tails, until you get a head, what is the chance that it takes five flips until you get a head?

Suppose you are throwing three darts and you have a one third chance of hitting the bull's eye. Each throw is independent of one another. What is the chance of hitting the bull's eye at least once?

A particle travels left with probability one sixth and right with probability five sixths. Each movement is independent of the others. What is the chance that after three movements, the particle ends up one unit to the right?

During a week's worth of soccer practice, a player practices total free kicks and has a chance of scoring. What is the probability that he or she scored at least times? Assume each shot is independent.

Which of the following would be considered a binomial experiment?