How do you determine the total mechanical energy stored of an object

An objects ability to do work is measured by its mechanical energy, or the sum the objects kinetic energy and potential energy. Mechanical energy is due to the position or movement of an object. The formula for mechanical energy is mechanical energy=kinetic energy + potential energy.

The answer is probably c. xylem

No. an alpha particle is a pair of protons and a pair of neutrons, i.e. a helium