Why is Single Whip Called Single Whip

One of the funny things about the martial arts I teach is that when teachers don't understand a movement they are likely to make up an overly-complex answer.

Over the years, I have heard all sorts of explanations about why Single Whip is called Single Whip.
A lot of stuff about Qi, and a lot of stuff about the entire body moving as a singe whip.
It's really simple, folks. Single whip is called Single Whip because only one arm is doing the whip.
That's it. The Hook Hand is holding something in place. The other arm is performing a whip, which is a type of scissor throw. In a lot of styles, the arm also performs a compression throw and a sail.

I'll update this with pictures as soon as I have time. The bold terms are things you can look up.