Consider the observation that many school shootings have been perpetrated by people with a history of playing violent video games. in this scenario, what could the third variable be?

The right option is "the shooters history of being bullied"

Explanation:

People with a history of being bullied turns out to be bullies or portray a high level of violent behaviors. There have been studies that shows a correlation between playing violent video games and violence. There have also been studies that suggest that people who have a history of being bullied will grow up being bullies and displaying several violent conducts.

bro these r easy u may have to do them urself bro. lol jk the answer is two for nimber one, and for question number two sahel boi xd have fun get rekt m8

good question. i'll be looking into that. (this is a joke sir)