A student was using the periodic table to organize elements based on their ionization energy from lowest to highest. At the end of the class period, the student left one of the 4 spaces blank. It looked like this: Ba, Co, , He.

Which of the following elements would best fit into this model?

A.
N would go into the blank because it fits the diagonal trend that points towards the upper right.

B.
Se would go into the blank because it fits the diagonal trend that points towards lower left.

C.
Kr would go into the blank because it is a noble gas and has a lower ionization energy than helium but higher than cobalt.

D.
Sb would go into the blank because it has more energy levels than cobalt which gives it a higher ionization energy than cobalt but less than helium.