In a lewis dot diagram, the electrons shown * a) are in the innermost energy level b) always equal the number of protons c) are in the outermost energy level d) always add up to an even number

Your answer would be C. Lewis Dot diagrams are one of the principal mechanisms in learning how the atoms in molecular structures interact, and this is influenced by the outermost shell of electrons. This eliminates A.

Molecules and elements are not always as found on the periodic table; depending on the reactions associated with an element, they could be left with more or less electrons than normal. This eliminates B and D, as electrons don’t have to conform to the even-rule.

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.