Explanation:

- The masseter muscle is indeed located in the jaw. It plays a crucial role in chewing by allowing the closure of the jaw. It is recognized for its strength relative to its weight.

- The muscles in the hand are responsible for intricate and delicate movements but are not considered the strongest by weight.

- The chest muscles, such as the pectorals, are vital for arm movement and breathing but do not possess the strength characteristics of the masseter.

- The thigh hosts large muscles like the quadriceps, noteworthy for their size and power, but not weight-relative strength.

The correct answer is: Option 1, jaw.