Directions: Pick the odd one out.

Foot, goose, tooth, moon, man

Correct. The four words - foot, goose, tooth, and man – follow the same rule while forming the plurals (by changing the inside vowel/vowels of the words). Thus, the plural forms of these words are - feet, geese, teeth and men. The word ‘moon’ is an odd one here since it forms the plural by adding –s to the singular noun.