Final answer:
The slope between the points (-1, 10) and (5, 10) is calculated to be 0, indicating a horizontal line, hence the correct answer is B. 0.
Step-by-step explanation:
The question asks to find the slope between the two points (-1, 10) and (5, 10). The slope of a line is calculated by the change in y divided by the change in x (rise over run). In this case, the change in y (y2 - y1) is 10 - 10 = 0 and the change in x (x2 - x1) is 5 - (-1) = 6. Therefore, the slope is 0/6, which simplifies to 0. The correct answer is B. 0, indicating that the line is horizontal.