Which condition is characterized by emaciation and wasting away in an infant due to malnutrition?

Marasmus is indeed the correct answer for the condition characterized by emaciation and wasting away in an infant due to malnutrition. This condition specifically arises from a severe deficiency in caloric intake, which leads to significant weight loss and a depletion of muscle and fat stores in the body. The effects of marasmus are most evident in infants and young children who are not receiving enough nutrients, particularly from protein and caloric sources.

In this state, the body's energy needs cannot be met, resulting in a frail appearance, growth failure, and susceptibility to infections due to a weakened immune system. Understanding marasmus is crucial in the context of malnutrition, as it highlights the importance of adequate dietary intake for the health and development of infants.

Other conditions listed are related to malnutrition but differ in their manifestations and specific deficiencies. Scurvy is primarily due to a vitamin C deficiency, while kwashiorkor is related to severe protein deficiency leading to a different set of symptoms, such as edema and fatty liver. Obesity, on the other hand, is characterized by an excess of nutrients rather than a deficiency, thus making it unrelated to this question about malnutrition in infants.