Question

Which one of the following words illustrates the addition of a vowel suffix? A. Tenderness B. Likelier C. Careful D. Dangerously

Answer 1

Technically none of the above, as none of the words are vowels.

C may be the best answer though, depending on the context; if it's a command to "be careful," for example.

Answer 2

I believe it's B. Likelier
Because the word is 'likely' ending in a y, you remove the vowl 'y' and make it 'likelier'