Multi-choice problem: Continue writing the next sentence in this paragraph:

How to clicker train a cat 
Get a clicker. 
A clicker is a small plastic box with a metal tab in it. When you press it, it makes a clicking sound.

Pick from: a). Once your cat hears the clicking, you can use the clicker. Clicking the clicker is a way to increase the amount of " click " of treats you give your cat.; b). These are available online or in pet stores, and they cost as little as $1. These are commonly used to train dogs and cats.; c). It gives your cat a signal that it is prepared to attack. If you click it just a couple of times, your cat will bite it and give it a treat.; d). You will hear it clapping, howling, and then repeating a phrase as you pet your cat. The clicker will help you control your cat's movements when you clicker train it.;
b).