Not the last as apostrophes are not used for plurals, and the second sounds strange, so i believe it is the first.
B. Tans mother could think of several ways to answer a question like the one described in the excerpt
Monitor is a concrete noun.
A concrete noun is something material. Basically, just remember that if you can touch it, it's concrete!
Abstract nouns are usually feelings, such as anger, happiness, sadness. If you can't touch it, it's abstract!
If you have any questions about how to differentiate concrete and abstract nouns, just ask!
Good luck :))
Explanation:
form an idea of the amount or number evaluation means