Research indicates that positive affect and emotions can impact physical health by:

The correct answer reflects the comprehensive impact of positive affect and emotions on physical health, as research has demonstrated that positive emotions can contribute to overall wellbeing in a variety of ways.

When considering how positive affect can decrease pain, studies have shown that positive emotions can lead to higher pain tolerance and lower reports of pain. This is largely due to the way positive feelings can alter neural pathways and influence the body's pain perception mechanisms.

Enhancing immune function is another area where positive emotions play a significant role. Research indicates that those with a positive mindset have better immune responses, which can help in fighting off illnesses and infections more effectively. Positive emotions are associated with lower levels of inflammation and improved responses to vaccines, showcasing a clear link between emotional wellbeing and immune health.

Increased longevity is also well-documented, as individuals who maintain a positive outlook on life tend to have longer life expectancies. Factors contributing to this include better stress management, healthier lifestyle choices, and stronger social relationships—all of which are often bolstered by positive emotions.

Thus, the option that encompasses all of these benefits—decreasing pain, enhancing immune function, and increased longevity—best captures the multifaceted influence of positive emotions on physical health.