Answer:
Steadier
Explanation:
Suffixes are a letter or group of letters added to the ending of words to change their meaning or function. These useful, shapeshifting tools can be as small as -s, and -ed, or can be larger additions such as -ation, and -ious.
None of the other words you listed (prepare, between, retry) have a suffix. If they had suffixes they would be prepared, preparation, retried, etc.)
