Final answer:
Correlational and experimental research offer explanations for the effectiveness of meditation in reducing stress, which include increased serotonin levels, enhanced cognitive function, and reduction in cortisol levels.
Step-by-step explanation:
The explanation that is not provided by correlational and experimental research for the effectiveness of meditation in reducing stress is activation of the fight-or-flight response. Instead, research suggests that meditation can lead to increased serotonin levels, which can promote feelings of well-being and relaxation. Additionally, meditation has been found to enhance cognitive function by activating the prefrontal cortex and promoting flexibility in cognition and affect. Furthermore, meditation can lead to a reduction in cortisol levels, which is a hormone associated with stress.