Answer:
The right choice is:
B. 21, 21, 53.
Step-by-step explanation:
Atomic Number = Number of electrons = Number of protons
So, the No. of protons (A) = Number of electrons =21
Atomic Number (B) = Number of electrons =21
Mass number (C) = Number of electrons + Number of neutrons = 21 + 32 = 53
So, the right choice is:
B. 21, 21, 53.