The object with the most mass, which would presumably be the boulder, will have the most gravitational potential energy if it's falling from the same height as the mango and subject to the same acceleration due to gravity.
Gravitational potential energy is equal to the mass of the object multiplied by acceleration due to gravity and by its height:
PE = mgh
Gravitational potential energy is the energy an object has due to its position. An object that has more mass or is at a greater height has more PE. As an object falls gravitational potential energy is converted to kinetic energy (KE), which is energy of motion. A falling object has maximum potential energy at its highest point, and the instant before it hits the ground it has maximum KE and minimum PE. KE = 1/2 (mass)(velocity)^2.