Answer:
The answer is A, Gilberto places used sharps in a bio-hazard container for the incinerator.
The answer is tighten and contract.
In order for the students to pull the rope their muscles will need to tighten and contract so they are able to continuously pull with all their strength and power. Relaxed or twitched muscles will result in release of the rope.
You use it by first making a observation, second ask questions, third do background research, and fourth form a hypothesis
