The correct option is
A Protein deficiency
Marasmus is one of the three forms of serious protein-energy malnutrition (PEM). The other two forms are kwashiorkor (KW) and marasmic KW. Marasmus is a condition primarily caused by a deficiency in calories and energy, whereas kwashiorkor indicates an associated protein deficiency, resulting in an edematous appearance. So, the correct option is 'Protein deficiency'.