Answer:
Test to see whether a Carbon Monoxide detector works
Explanation:
This was kinda tricky...
The first one which is the loaded firearm is not the best one because one of the kids can grab the gun and think that its a toy, and well things go bad from there. The second one which is the Medicine in the lower cabinet would have been good if it was on a high shelf where none of the kids can grab it and take one thinking that it is candy. And the last one which is the Chemicals are definitely not right and is kinda dumb.
D. because for benching you don't want them to drop it on their chest or stomach so you place your arms under the bar not under them
