What are the next steps they would use to determine the gravitational mass and the inertial mass in order to compare the two values for...?

Physics students have been given a spring that can hang from a horizontal supporting rod, a set of known masses to hang on the spring, a motion detector to place under the spring, and an unknown mass. They can determine the spring constant by graphing the weight of the known masses versus the elongation of the spring. A graph of this data can be used to find the spring constant. What are the next steps they would use to determine the gravitational mass and the inertial mass in order to compare the two values for the unknown? 

Select TWO answers.

A. Hang the unknown mass on the spring and allow it to settle into equilibrium. Measure the length of the stretched spring with the motion detector and multiply by the spring constant to yield the gravitational mass.

B. Pull down on the unknown mass and allow it to vibrate. Determine the period from a graph of period vs displacement by measuring the time from peak-to-peak. Calculate the inertial mass from the period and spring constant.

C. Hang the unknown mass on the spring and allow it to settle into equilibrium. Measure the change in length of the stretched spring with the unknown mass and use this to determine the weight and gravitational mass.

D. Pull down on the unknown mass and allow it to vibrate. Graph period vs. displacement. The elongation is the amplitude of the graph. Use this to calculate the inertial mass.