Which of the following contains an error in apostrophe usage? what did you do with the houseplant's i bought yesterday? it was obvious that there weren't any donuts left from the meeting. it's a good time to reassess our strengths and weaknesses as a company. the janitors' brooms need to be replaced as soon as possible.

The sentence which contains an error in apostrophe usage is the first one - What did you do with the houseplant's I bought yesterday?
The error is in the word "houseplant's" because that apostrophe is redundant, meaning that you don't have to use it here because it changes the meaning. You want to say that there are more than one houseplant, and to create the plural form, you just need to add -s, without the apostrophe. 

Idk they both are both really good