Final answer:
Lactose intolerance is caused by a deficiency of the enzyme lactase, leading to symptoms after consuming dairy. It is managed with lactose-free foods or enzyme supplements. Hence, option (a) is correct.
Step-by-step explanation:
Lactose intolerance is caused by lactase deficiency. The condition occurs when the absorptive cells of the small intestine do not produce sufficient levels of lactase, the enzyme necessary for the digestion of lactose, which is the sugar found in milk. This enzyme deficit results in symptoms such as diarrhea, gas, bloating, abdominal cramps, and nausea after consuming dairy products.
Lactose intolerance is particularly common among certain populations, including many Asian adults, as well as other individuals around the world. Management of lactose intolerance generally involves the avoidance of lactose-containing foods, the use of lactose-free products, or enzyme supplements to aid digestion.