D - brisk.
It is basically a synonym for fast and is an adjective which is what is missing .
Do not use AED if victim is lying in water.
Do not use AED if chest is covered with sweat or water.
Do not put an AED pad over a medication patch.
Do not place AED pad over a pacemaker (hard lump under chest skin).
B. Exercise strengthens the bones so if you go without exercise your bones become weak.
Options? and I think its skeletal system.