Question: Some students measure the mass of a small pile of leaves before and after the leaves decompose. Each time the students measure the mass, they place a container with the decomposing leaves on a balance. Before recording the mass of the leaves, the students must do which of the following?

  Options: 
 A. Subtract the mass of the container
 B. Add leaves from other plants to the container
 C. Allow the leaves to settle in the container for a few days
 D. Use a metric ruler to measure the volume of the container
Answer: A