Answer:
c. stool sample
Step-by-step explanation:
"Malabsorption syndrome" refers to the inability of the body's small intestine to absorb fats, carbohydrates, vitamins, minerals, fluids, etc. A person with this syndrome often has a chronic diarrhea. In order to check whether a person has this syndrome, the first diagnostic test is the "stool test." Thus, it is important to check the "stool sample" of the patient first.
Among the diagnostic tests mentioned above, the "stool test" is the cheapest, easiest and less-invasive test that a person may undergo. This is the reason why it often comes first.