Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.

[Q]: Category: ocean 
Words: current, wave, whirlpool, sea, data sets
[A]: data sets


[Q]: Category: police punishment 
Words: prime, penalty, fine, mad, arrest
[A]: mad


[Q]: Category: aesthetic characteristic 
Words: flaxen, pale, unprejudiced, fair, milky
[A]:
unprejudiced