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 sandwich 
Words: submarine, group, club, roll, grilled cheese

Answer: group


Question: Category: emotional status 
Words: down, emotional upsets, disgusted, shameful, sliding

Answer: sliding


Question: Category: construction 
Words: concrete pourer, digger, ostrich, davit, crane

Answer:
ostrich