A vending machine has three buttons, labeled A, B, and C. The cost is the same for all three buttons. If you press A, you get a pound of fertilizer. If you press B, you get a pet rat. If you press C, you randomly get either fertilizer or a pet rat. Given a situation where a person wants both fertilizer and a rat, but only has money for one or the other, which button would be used the most, and why? Which one would get pushed least?