Final answer:
Resistance to stress is at its highest in (B) Phase 2 of the General Adaptation Syndrome, also known as the stage of resistance.
Step-by-step explanation:
Resistance to stress is greatest during the stage of resistance, which is Phase 2 of the General Adaptation Syndrome (GAS). During the alarm reaction or Phase 1, the body initially reacts to stress with a fight-or-flight response, which is an immediate and short-term reaction to stress. If the stressor persists, the body then enters Phase 2, the stage of resistance, where the shock from the alarm reaction has worn off and the body has adapted to the stressor, albeit with less intense reactions than in the initial phase.
The stage of resistance is designed to help the body cope with prolonged stressors by adjusting its responses. After the stage of resistance, if the stress continues, the body will eventually reach the stage of exhaustion, which is Phase 3, where resources are depleted and health problems may arise.