Final answer:
The slope of the vertical line x = -1 is undefined because it has no rise over run, which would require division by zero. The correct answer is A) Undefined.
Step-by-step explanation:
The equation x = -1 represents a vertical line on the Cartesian coordinate system. Since a vertical line goes straight up and down, it has an undefined slope. A vertical line does not have a rise over run, meaning that we cannot calculate a slope because we would be dividing by zero, which is not allowed in mathematics. On the other hand, a horizontal line, such as y = a constant, would have a slope of zero because the rise is zero and there is no change as you move along the line. Thus, the correct answer to the question 'What is the slope of the line x = -1?' is A) Undefined.
The line x = -1 represents a vertical line that passes through the x-coordinate of -1 on the Cartesian plane. Since a vertical line has no slope, the correct answer is A) Undefined.