Chapter 2 - Graphs and Functions - 2.5 Equations of Lines and Linear Models - 2.5 Exercises - Page 242: 10

$A$

RECALL: The graph of the equation $y=k$ where $k$ is a real number is a horizontal line whose y-intercept is $(0, k)$. Notice that the graph in Option A is a horizontal line whose y-intercept is $(0, 4)$. Thus, the graph of the given equation is the one in Option $A$.