Clayton is a 19-year-old college student. He avoids milk, because he claims drinking the beverage upsets his stomach and gives him intestinal "gas." However, he can eat yogurt and certain types of cheese without experiencing any symptoms. Based on this information, Clayton probably has:

a) botulism poisoning.

b) lactose intolerance.

c)cystic fibrosis.

d) amylase deficiency.

b) lactose intolerance.

Explanation:

Lactose intolerance is the inability to digest lactose in milk and dairy products due to the deficiency or complete absence of the enzyme lactase. Lactase converts lactose into glucose and galactose.In this case, Clayton is intolerant to milk but can digest yogurt and some kinds of cheeses.Yogurt and aged cheeses contain trace amounts of lactose. During the manufacturing of cheese and yogurt, most of the lactose is drained along with the water and whey proteins. In aged cheeses such as Cheddar, Parmesan and Swiss, the trace, left over lactose is further drained during the process of aging.