Students attach a thin strip of metal to a table so that the strip is horizontal in relation to the ground. A section of the strip hangs off the edge of the table. A mass is secured to the end of the hanging section of the strip and is then displaced so that the mass-strip system oscillates, as shown in the figure. Students make various measurements of the net force \( F \) exerted on the mass as a result of the force due to gravity and the normal force from the strip, the vertical position \( y \) of the mass above and below its equilibrium position \( y_0 \), and the period of oscillation \( T \) when the mass is displaced by different amplitudes \( A \). Which of the following explanations is correct about the evidence required to conclude that the mass undergoes simple harmonic motion?