Choice A is the correct answer. Identify the horizontal line.

1. Form: $y = 5$ can be written as $y = 0x + 5$.
2. Slope: The coefficient of $x$ is 0.
3. Visual: This is a horizontal line.

💡 Strategic Tip: "Y equals number" means zero slope. "X equals number" means undefined slope.

Choice B is incorrect because it is vertical (undefined slope). Choice C is incorrect because slope is 5. Choice D is incorrect because slope is 1.