Answer :

A horizontal line that intersects the graph at (0,4)
AL2006
-- Find any point where y=4

-- Find another point where y=4

-- With your ruler, draw a line between the two points.
You have a horizontal line, and every point on it has y=4 no matter what 'x' is.

The equation for every straight line is [ y = mx+b ].

This is the line where (m = 0) and (b = 4).