Answer:
D ) Elastic and Gravitational
Explanation:
Mechanical energy is defined as the sum of elastic, potential and kinetic energies.
Therefore potential energy and gravitational or potential energy are contemplated within the definition of mechanical energy.
[tex]E_{M} = E_{e}+E_{k}+E_{p}\\where:\\E_{M}= Mechanical Energy\\E_{e} = elastic energy\\E_{k} = kinetic energy\\E_{p}= potential energy[/tex]
The units for energy are given in joules [J] for the SI and Btu for the IP system
