• Red Muscle vs. White Muscle Fibers:
• Red Muscle Fibers (Type I, Slow-Twitch): Contain abundant mitochondria, a dense capillary bed, and high concentrations of myoglobin. They rely primarily on aerobic cellular respiration and oxidative phosphorylation to generate ATP for sustained, fatigue-resistant endurance contractions.
• White Muscle Fibers (Type IIb, Fast-Twitch): Possess fewer mitochondria, lower myoglobin levels, and high glycogen content; they rely on anaerobic glycolysis for rapid, high-power bursts of contraction.

Correct option: (2) Red muscles