Assertion: The average mass of one Mg atom is `24.305 amu`, which is not actual mass of one Mg atom.
Reason: Three isotopes, `24 Mg, 25 Mg and 26 Mg`, of Mg are found in nature.
A. Both assertion and reason are correct and reason is the correct explanation of the assertion.
B. Both assertion and reason are correct but reason is not the correct explanation of assertion.
C. Assertion is correct but reason is incorrect.
D. Assertion is incorrect but reason is correct.