Is this
a. a function, but not one-to-one
b. one-to-one function
c. not a function

We can use the vertical line test

if we can draw a vertical line that passes through the points twice, then it is not a function (remember, every x has 1 y coresponding)

we can't draw any vertical line

this is a floor function actually
the empty circles are like the > or < sign
the filled in circles are like ≤ or ≥

this is a function  and it is one-to-one because every x goes with 1 y
da answer is B