Question

a person is standing in front of the bookcase. this statement describes the persons position motion speed mass

Explanation:

The statement "A person is standing in front of the bookcase" tells us where the person is located relative to the book - case, which is a description of position. Motion would involve change in position over time, speed is the rate of change of position, and mass is the amount of matter in the person, none of which are described here.

Answer:

position