$A$ demonstration apparatus on a table in the lab is shown in the diagram. It consists of a metal track (shown as a thick solid line in the figure) along which a perfectly spherical marble can roll without slipping. In one run,the marble is released from rest at a height $h$ above the table on the left section,rolls down one side and then up the other side without slipping,briefly stopping when it has reached $h_1$. Assuming the table to be horizontal and neglecting air drag as well as any energy loss due to rolling,which of the following is true?

• A
  $h_1 < h$ always,because the friction that keeps the ball rolling must dissipate energy.
• B
  $h_1 = h$,since total mechanical energy is conserved.
• C
  $h_1 = h$ only if tilt angles $\phi$ and $\theta$ are equal.
• D
  $h_1 = h$ only if tilt angle $\phi$ is larger than $\theta$.