Final answer:
The equation of the horizontal line passing through (-2, 6) is y = 6, which represents a constant y-coordinate for all points on the line.
Step-by-step explanation:
The equation of the horizontal line that passes through the point (-2, 6) is y = 6. This is because a horizontal line has a slope of 0, which means the y-coordinate for all points on the line will remain constant while the x-coordinate can vary. In this case, since the given point has a y-coordinate of 6, the equation of the line must be y = 6, reflecting that all points on the line will have the same y-coordinate of 6. The option (a) y = 6 is the correct choice, indicating it is indeed a horizontal line at some positive value.