Which of the following is a sign of malabsorption in a patient?

A sign of malabsorption in a patient is the presence of greasy stools, also known as steatorrhea. This occurs when the intestines are unable to properly absorb fats and oils from the diet, leading to an excess of unabsorbed fat in the stool. The stools may appear pale and float due to the high fat content, and patients often report a foul odor. Steatorrhea is a classic manifestation of conditions that cause malabsorption, such as celiac disease, chronic pancreatitis, or cystic fibrosis.

In contrast, increased appetite can suggest other issues but is not typically associated with malabsorption. Frequent vomiting might indicate other gastrointestinal problems but does not specifically indicate malabsorption. Intestinal obstruction presents with entirely different symptoms and is a mechanical blockage rather than a functional absorption problem. Thus, greasy stools are a direct reflection of the inability to absorb fats, making it the clear sign of malabsorption.