Final answer:
Strength training is the most beneficial modality for Phases 1, 4, and 5 of the OPT model.
Step-by-step explanation:
The modality that will provide the most benefits to Phases 1, 4, and 5 of the OPT model is strength training. Strength training, which is considered an anaerobic exercise, focuses on increasing muscle strength. During Phase 1 of the OPT model, strength training helps build a solid foundation. In Phases 4 and 5, it is essential for improving overall strength and power.