Problem

Let us define a region

R

xy

-plane as a set of points

(x, y)

satisfying

[x^2] = [y]

(where

[x]

denotes greatest integer

\le x

), then the region

R

defines a. a parabola whose axis is horizontal b. a parabola whose axis is vertical c. integer point of the parabola

y = x^2

d. None of the above