Hi, you've asked an incomplete question. I inferred you need more information about suffixes.
Explanation:
Well, generally in the English language suffixes are words added to the end of a word to give a new meaning.
For example, the word 'avail' is one such word that can have a new meaning after the addition of a suffix like "able". By adding avail+able we form "available". Another word is 'quick' by the addition of the suffix 'ly' forms 'quickly'.
Answer: The ending is able
Explanation: It is group 1 because avail is a whole word all you do is add an ending