Answer:
The correct option is 2.
Explanation:
The given function is

It is a greatest integer function.
The parent greatest integer function is

This function is defined as

The parent function shifts 1 units up to get the given function.

Left end of each floor is a closed circle because the sign of inequality is ≤ and right end of each floor is an open circle because the sign of inequality is <.
Therefore the correct option is 2.