Answer
The correct answer is: (c) the same value as at every other point in the orbit.
Work Step by Step
By conservation of energy, the sum of the kinetic energy and the gravitational potential energy is constant. At perihelion, the sum of the gravitational potential energy and the kinetic energy must be the same as at every other point on its orbit. Therefore, at perihelion, the mechanical energy of Pluto's orbit must have the same value as at every other point on its orbit.
The correct answer is: (c) the same value as at every other point in the orbit.