When is a person considered undernourished? 

A)  when there is not enough meat in their diet 
B)  when they eat too much junk food 
C)  when they eat fewer than the basic minimum number of daily calories 
D)  when they suffer from poor food quality

Undernourishment is a condition that arises due to the lack of essential nutrients in the body. It occurs when a person consumes fewer than the basic minimum number of daily calories required to sustain healthy body weight and functions. Options A, B, and D are incorrect because mere meat deficiency or poor food quality, or excessive junk food consumption may not necessarily result in undernourishment.