The correct answer is A.
By trying out the equipment first at a fitness club you can make an informed decision as to whether you will use the equipment at home, if you are able to use the equipment, if you will get any benefit from it, if you enjoy using it. You don't want to make an unnecessary purchase of a piece of equipment you will never use and waste your money.
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.
