C

Step 1: The atomic mass unit (a.m.u) is a standard unit of mass used in atomic and molecular physics. It is defined as one twelfth of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state.
Step 2: The equivalent energy of mass can be calculated using Einstein's famous equation, $E = mc^2$, where:
- $E$ is the energy in joules,
- $m$ is the mass in kilograms,
- $c$ is the speed of light in vacuum (approximately $3 imes 10^8$ m/s).
Step 3: To find the energy equivalent of 1 a.m.u., we need to use the conversion factor for a.m.u. to kilograms: 1 a.m.u. is approximately $1.66 imes 10^{-27}$ kg.
Step 4: Substitute the values into the equation:
$$E = (1.66 imes 10^{-27} ext{ kg}) imes (3 imes 10^8 ext{ m/s})^2$$
$$E ext{ (in joules)} = 1.66 imes 10^{-27} imes 9 imes 10^{16} = 1.494 imes 10^{-10} ext{ J}$$
Step 5: To convert joules to electronvolts (eV), we use the conversion $1 ext{ eV} = 1.6 imes 10^{-19} ext{ J}$. Therefore,
$$E ext{ (in eV)} = \frac{1.494 imes 10^{-10}}{1.6 imes 10^{-19}} ext{ eV} ext{ (calculating)}$$
$$E ext{ (in eV)} \approx 931.5 ext{ MeV}$$
Step 6: Rounding this gives us approximately 931 MeV.
Therefore, the correct answer is Option C: 931 MeV.