D. All of the above. Weightlifting has been found to provide all these advantages, from boosting the immune system to providing cognitive benefits.
A. True. Meat-heavy diets were once sold as the only way to build significant muscle, but with the advent of protein-rich plant-based meat substitutes, it's entirely possible to lift while vegan.
B. Meditation. Many athletes meditate daily. Meditation helps calm and focus the brain, and breathing techniques can help weightlifters succeed.