Final answer:
Infants require the most dietary protein per pound of body weight due to their rapid growth and development needs.
Step-by-step explanation:
The child that requires the most dietary protein per pound of body weight would be an infant. During the rapid growth phase of infancy, protein is crucial for cell growth, brain development, and the formation of enzymes and immune function. Infants have higher protein needs relative to their body weight when compared to toddlers, adolescents, and adults. As children grow, their protein requirements per pound of body weight decrease, with adults generally needing less compared to children.