Which of the following statements is correct?

The correct answer is option 2. Atomic radius decreases across a period and increases down a group in the periodic table.

The correct statement regarding atomic radius trends in the periodic table is: Atomic radius decreases across a period and increases down a group.

Across a period (from left to right):  As you move from left to right across a period, the atomic radius generally decreases. This is because electrons are added to the same energy level, but the increasing positive charge in the nucleus pulls the electrons closer.

Down a group (top to bottom):  As you move down a group, the atomic radius generally increases. This is because electrons are added to higher energy levels, increasing the average distance of the outer electrons from the nucleus.

Therefore, option 2 is the correct statement.