Which statement best describes a milk allergy?

A.  The body's inability to digest significant amounts of lactose, the predominant sugar in milk.

B.  The immune system's response to one or more of the proteins found in cow's milk.

C.  The digestive system's response to one or more of the proteins found in cow's milk.

The correct answer is (B) – The immune system’s response to one or more of the proteins found in cow’s milk.  Cow's milk is one of the most frequent food allergens. There are many protein allergens in cow's milk that cause allergic reactions. Casein and whey are the two main components. The curd that forms when milk is left to sour, is called casein. The watery part that is left after the curd is removed is called whey.