What happens to the atomic size as you go down the group?

Correct option is C

The correct answer is (c) Increases.
 The atomic size increases down the group.
 This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases inspite the increase in nuclear charge.
 As the number of electron shells increases, there's a greater repulsion between them, causing the shells to expand and the atom to become larger.
 A positively charged subatomic particle found in the nucleus of an atom is called proton.
 Ernest Rutherford's gold foil experiment (1911) proved the existence of a dense, positively charged nucleus.