Final answer:
Lean body tissues contain significantly more water than fat, with the estimated percent of water in lean tissue being approximately 75%.
Step-by-step explanation:
Compared to fat, lean body tissues contain significantly more water. The estimated percent of water in lean tissue is roughly 75%. This is because water makes up a large proportion of the adult human body, ranging from about 50-70% of body weight. Specifically, intracellular fluid, which is the fluid within cells, comprises approximately 50% of body weight in lean individuals, and the extracellular fluid, which includes interstitial fluid and plasma, represents about 20% of body weight. Therefore, considering that lean tissue is devoid of much of the fat that displaces water, it is much richer in water content. Organs such as the brain and kidneys are particularly water-rich, comprising about 80-85% water. Hence, option d. 75% is the correct choice for the estimated percent of water in lean tissue.