You could also try pattern match questions. They are nice if you want them to think up the answers rather than recognizing them in options.
Give this a try as the question:
What are the two bases on which solids moisture can be reported? ____20x1____
(The 20x1 will create a 20 character long 1 row tall entry box.)
Then code to accept right answers.
Different people will put more or less complicated pattern matches. But I'd probably give credit for almost anything that had both "wet" and "dry" in it. So in answer 1 I'd put
and give 100% for that.
For answer 2, I might do
I'd give 50% for answer 2 and provide feedback that they got one of the two correct.
There are various other things you can do depending on what you are worried students might do in filling out the box.