Answer: The correct answer is Option e.
Step-by-step explanation:
All these elements belong to period 3 in a periodic table.
Atomic size is defined as the distance between the nucleus and the outermost shell of an element.
In a group, electrons get added up in the same shell and the attraction between the nucleus and the outermost electron added increases. This results in the contraction of size of an element.
Period 3 elements are in the order Sodium, Magnesium, Aluminium, Silicon and Phosphorous.
Hence, phosphorous has the smallest atomic size. Therefore, the correct answer is option e.