Bound morphemes

Could someone help me understand bound and free morphemes?
I had a quiz for my Intro to Speech Path class and got this question wrong:

"Which of the following is an example of a bound morpheme?
a. the 'per' in perfect
b. the 'son' in person
c. the 'ize' in symbolize
d. all of these"

The correct answer is c. However, I don't understand it. Obviously "ize" is a bound morpheme. It can't stand alone. However, it doesn't seem to me like the "per" in perfect can stand alone and still maintain the same meaning. The same goes for "son" in person. Yes, I've asked my professor, but it wasn't any help.

Is the answer c because "symbol" in symbolize is a free morpheme?

Sorry if this isn't the place for this.
Let's back up.

Is per in perfect a morpheme? Forget bound or unbound, is it a morpheme at all? No, it is not. It does not carry any sort of meaning by itself. It doesn't negate or pluralize or anything, it doesn't carry any meaning by itself. Same for son in person. It seems like a morpheme because son is also a word (morpheme) that means male child, but in the word person, son carries no meaning.

Let's look at symbolize. That has 2 morphemes. Symbol is one morpheme. It is a unit that carries meaning. It can't be broken down any further. So is ize. Ize means roughly, "to make." So symbolize is made up of 2 morphemes and means something like to make into a symbol.

Now, symbol can stand alone, right, but ize must be attached to another morpheme. We don't just go around saying ize. We say symbolize, materialize, generalize, sterilize, etc. So it is a bound morpheme.

In fact, in the whole question, it seems like the other answers weren't morphemes at all.

Does that make more sense?
Yes, that makes perfect sense. I was assuming that if something wasn't a bound morpheme, it had to be a free morpheme, and I knew "per" and "son" couldn't be free morphemes. Thank you.
Well, that is true, but it only applies to morphemes. The other ones weren't even morphemes.

So the first step in figuring out the answer to that question is finding the morphemes. Then once you've done that you can determine which ones are free and which are bound. Take it step by step.

Glad I could help!