Answer: The correct answer is Option D.
Explanation:
Atomic mass of an atom is defined as the sum of number of neutrons and number of protons that are present in an atom. It is represented as 'A'.
Atomic number = Number of protons + Number of neutrons
We are given:
Number of protons = 6
Number of neutrons = 6
Number of electrons = 6
Atomic mass = 6 + 6 = 12
Hence, the correct answer is Option D.
