What type of analysis is performed to assess the composition of liquid waste?

Urinalysis is the correct choice for assessing the composition of liquid waste because it specifically examines urine, which is a waste product produced by the kidneys. This type of analysis provides valuable information about a person's health, including the presence of substances like proteins, glucose, electrolytes, and various metabolites, which can indicate different medical conditions.

In contrast, serum analysis focuses on blood serum components, primarily measuring biochemical substances for various health evaluations. Blood tests pertain to analyzing components found in whole blood, such as red and white blood cells, platelets, and various chemical levels. Stool examination assesses fecal matter to identify digestive processes and diseases related to the gastrointestinal tract. Therefore, urinalysis is specifically designed to evaluate liquid waste generated by the urinary system, making it the most relevant choice for this question.