Answer:
Reason
Step-by-step explanation:
A word is composed of one or more morphemes (the smallest unit of the meaning of a word but that can not stand on its own), and these morphemes may be divided into root words (which hold the most basic meaning of a word), prefixes (Added before a root word) and suffixes (Added at the end of a root word).
The word "unreasonable" has all three types of morphemes:
- "Un" is the prefix and it means not, reverse action, deprive of, release from.
- "Reason" is the root word and it means "a sufficient ground of explanation or of logical defense."
- "Able" is the suffix and it means capable of, susceptible of, fit for, tending to or given to.