B. Water is a polar molecule that acts as a universal solvent.
The "set-point theory" implies that each individual is genetically programmed to carry a particular amount of body weight.
The set point is the weight range in which your specific body is programmed to work. The set point theory trusts that a man's body will battle to keep up that specific weight range.
I think the correct answer from the choices listed above is the third option. The barrel of a gun is also known as bore. The barrel is the metal tube which the bullet is fired and the bore is the inside of the barrel. It is the one closest to the barrel so it must be the answer.
I attached the image related to your concerned question.
In theory, the part of the brain that is responsible for the sleep wake cycle is the hypothalamus; specifically, the ventrolateral preoptic nucleus of the hypothalamus. In the image, the location of the hypothalamus is pointed by the green square.