Which method of terrorism involves using nerve gas to disable or kill an opponent?

Which method of terrorism involves is likely to slowly kill an opponent?

Terrorist act perpetrated by a group for any other purpose, most often of a religious nature

The goal of this type of terrorism is not to overthrow the government, but to protest a governmental policy or action.

The January 6, 2020 "insurrection" riot in Washington D.C. would be an example of which type of terrorism?