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.
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Question: Category: activity 
Words: dally, goodbye, fritter, whittle, dumpling

Answer: dumpling


Question: Category: physical activity 
Words: bend, jog, get down, duck, pig

Answer: pig


Question: Category: type of rigidity 
Words: concerted, hard, tough, firm, stiff

Answer:
concerted