Pick the odd one out:

In option B, friendship & enmity are antonyms.
In option C, often & seldom are also antonyms.
In option D, loyalty & treachery are antonyms. 
In option E, devotion & loathing are also antonyms.

In option A, we have wisdom & folly.

Wisdom means the quality of having experience, knowledge, and good judgement; the quality of being wise whereas Folly means lack of good sense; foolishness, mistake. In a way lack of folly is not an antonym of lack of wisdom. These two words are not perfect antonyms whereas in remaining 4 options the pair of word means exact opposite of each other. Hence, option A is the correct answer.