Complete the Following Statement: to Measure the Proper Length of an Object

Complete the following statement: To measure the proper length of an object moving relative to the surface of the earth, one must note the coordinates of points on the front and back ends

A) at the same time with respect to a clock at rest on the earth.
B) at different times with respect to a clock on the moving object.
C) at the same time with respect to a clock on the moving object.
D) at different times with respect to a clock at rest on the earth.
E) at the same time with respect to a clock moving at the same speed on the surface of the earth.