Option A as it represents a graph of a straight line, which is a function because it satisfies the vertical line test. Here option A is correct.
A relation is a function if every input has exactly one output. This means that for any value of x, there is only one possible value of y. Graphically, this means that a vertical line drawn at any x-value will intersect the graph of the relation at most once.
Option A is a graph of a straight line, which is a function because it passes the vertical line test. No matter where you draw a vertical line, it will only touch the graph once.
Option B is a graph of a circle, which is not a function because it fails the vertical line test. If you draw a vertical line anywhere inside the circle, it will touch the graph twice.
Option C is a graph of a parabola, which is a function because it passes the vertical line test. No matter where you draw a vertical line, it will only touch the graph once.
Option D is a graph of a hyperbola, which is not a function because it fails the vertical line test. If you draw a vertical line near the center of the hyperbola, it will touch the graph twice. Here option A is correct.