(C)
Since nitrogen is in the second row, its highest energy electron is at n = 2, which is the first number. The second number signifies that its outer electron is in a p-orbital. The third number indicates the third p-orbital to receive an electron, since nitrogen is the third element in the p-block in the periodic table. The last number is the magnetic spin quantum number and signifies that the highest energy electron is the only electron in the orbital.