What physiological change occurs to better facilitate movement away from danger?

The correct choice reflects the body’s response to danger, commonly referred to as the "fight-or-flight" response, governed by the sympathetic nervous system. When faced with a threat, the body prepares itself for rapid action. Enhanced muscle tension allows for greater strength and readiness to respond, enabling an individual to either fight or escape from the perceived danger more effectively. This increase in muscle tone and readiness supports quick movements that are crucial in high-stress situations.

The rationale for this physiological change lies in the body's overall strategy for survival. By enhancing muscle tension, the individual is able to react swiftly and efficiently, which could be the difference between safety and harm in a threatening environment.

Other potential options do not align with the body's adaptive strategies under stress. For instance, increased muscle relaxation would hinder quick movement, decreased heart rate would reduce blood flow and energy levels needed for a rapid response, and reduced blood flow to limbs would compromise the very muscles needed for effective movement away from danger. Thus, enhancing muscle tension is critical in the context of immediate self-preservation.