Final answer:
Blood is the body fluid compartment with a consistent volume (percentage of body weight) across infants, adult males, and adult females, making up about 8 percent of body weight.
Step-by-step explanation:
The body fluid compartment that has the same volume (percentage of body weight) in the infant, the adult male, and the adult female is the blood. Blood constitutes approximately 8 percent of adult body weight regardless of gender. This compartment consists of blood plasma and cells, with plasma being about 92 percent water.
While the total body water percentage varies with age and body composition, the proportion of blood to body weight remains consistent across these demographics.