The reason for the decrease in the atomic size of elements across a period is that?

A. nuclear charge increases while the outermost electrons are drawn closer to the nucleus
B. nuclear charge decreases while the outermost electrons are drawn closer to the nucleus
C. valence electrons increase across the period while the valence shell remains constant
D. nuclear charge decreases while the distance of the valence shell from the nucleus is increasing

Correct Answer: Option A

A. nuclear charge increases while the outermost electrons are drawn closer to the nucleus

Explanation

This is caused by the increase in the number of protons and electrons across a period.