The graph of the function f , where y = f ( x ) , gives

Choice A is correct. The given graph is a line, and the slope of a line is defined as the change in the value of $y$ for each increase in the value of $x$ by $1$. It’s given that $y$ represents the total cost, in dollars, and that $x$ represents the number of games. Therefore, the change in the value of $y$ for each increase in the value of $x$ by $1$ represents the change in total cost, in dollars, for each increase in the number of games by $1$. In other words, the slope represents the cost, in dollars, per game. The graph shows that when the value of $x$ increases from $0$ to $1$, the value of $y$ increases from $100$ to $125$. It follows that the slope is $25$, or the cost per game is $\$25$. Thus, the best interpretation of the slope of the graph is that each game costs $\$25$.

Choice B is incorrect. This is an interpretation of the y-intercept of the graph rather than the slope of the graph.

Choice C is incorrect. The slope of the graph is the cost per game, not the cost of the video game system.

Choice D is incorrect. Each game costs $\$25$, not $\$100$.