Final answer:
The appropriate force when an accelerative force acts on the body in a back-to-chest direction during acceleration is the inertial force. This sensation is due to the body's inertia resisting change in motion, not a real force pushing backward. The correct answer is D) Inertial force.
Step-by-step explanation:
The appropriate force that occurs when an accelerative force acts on the body in a back-to-chest direction during acceleration is the inertial force. In this scenario, when you are accelerating in a jet aircraft, it feels as though you are being pushed back into the seat. However, this sensation is due to the inertia of your body; the tendency to resist changes in motion according to Newton's first law. There isn't a real force pushing you backward; it's actually the seat that moves forward, pushing against your back, while your body wants to remain in its original state of rest or uniform motion.
This can also be experienced in a car when making a tight turn. You might feel like you are being thrown to the side opposite of the turn, which is also a result of inertial force, as your body attempts to maintain its linear motion while the car changes direction around you.
To summarize, the sensation you feel is not due to an actual force being exerted backwards on you but rather the inertial effects of your body resisting the forward acceleration of the vehicle you are in. The correct answer to the question is D) Inertial force.