instruction:
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.
question:
Category: type of rigidity 
Words: unbending, unyielding, inflexible, firm, streamline
answer:
streamline


question:
Category: construction 
Words: digger, concrete pourer, crane, derrick, excavator
answer:
derrick


question:
Category: police punishment 
Words: jail, wispy, fine, mad, arrest
answer:

mad