Final answer:
When the glider is climbing until it stalls, both the kinetic energy and potential energy of the glider are at their greatest at sea level.
Step-by-step explanation:
In this scenario, the glider is climbing until it stalls, assuming there is no drag. At the moment of stalling, the total energy of the glider is at its greatest. This means that both the kinetic energy and potential energy of the glider are at their greatest when the glider is at sea level climbing until it stalls.