Final answer:
Increasing muscular strength contributes to increasing lean tissue, decreasing body fat, and improving overall fitness, making option D (all of the above) the correct answer.
Step-by-step explanation:
Increasing muscular strength does indeed have multiple benefits. It can increase lean tissue, which refers to the growth of muscle mass that comes as a response to resistance training or other forms of anaerobic exercise. Muscle hypertrophy, or the growth of muscle cells, is an anabolic process that contributes to this increased muscle mass. Similarly, it can contribute to a decrease in body fat by improving metabolic rate, as muscle tissue burns more calories than fat tissue, even when at rest. And lastly, increasing muscular strength certainly serves to improve fitness levels overall, enhancing not only the muscular system but also contributing to better cardiovascular health, increased bone density, and improved cognitive function.
Therefore, the answer to the question is D. all of the above—increasing muscular strength helps increase lean tissue, decrease body fat, and improve fitness.