Textbook Problem

To which element does each of the following electron configurations correspond?

msp;  $\begin{array}{l}\text{a}.\text{ 1}{s}^{\text{2}}\text{2}{s}^{\text{2}}\text{2}{p}^{\text{6}}\text{3}{s}^{\text{2}}\text{3}{p}^{\text{6}}\text{4}{s}^{\text{2}}\text{3}{d}^{\text{1}0}\text{4}{p}^{\text{4}}\\ \text{b}.\text{ 1}{s}^{\text{2}}\text{2}{s}^{\text{2}}\text{2}{p}^{\text{6}}\text{4}{s}^{\text{2}}\text{3}{d}^{\text{1}}\\ \text{c}.\text{ 1}{s}^{\text{2}}\text{2}{s}^{\text{2}}\text{2}{p}^{\text{6}}\text{3}{s}^{\text{2}}\text{3}{p}^{\text{4}}\\ \text{d}.\text{ 1}{s}^{\text{2}}\text{2}{s}^{\text{2}}\text{2}{p}^{\text{6}}\text{3}{s}^{\text{2}}\text{3}{p}^{\text{6}}\text{4}{s}^{\text{2}}\text{3}{d}^{\text{1}0}\text{4}{p}^{\text{6}}\text{5}{s}^{\text{2}}\text{4}{d}^{\text{1}0}\text{5}{p}^{\text{5}}\end{array}$