DF congruent to AC and EF is common side
P=33+6.71
= 39.71
add 33+ 6.71
The step function is characteristic of the floor or ceiling functions, which map a real number to an integer. There's clearly a factor of 2, indicated by two units of y for every one unit of x.
The open and filled circles indicate, for example, f(1)=2, f(1.01)=4. That means we're rounding up, so we're using the ceiling function.

Answer: second choice