Based on slope, how do you know when two lines are parallel? A. The slope of one line must be equal to reciprocal of the other for the two to be parallel. B. The slope of one line must be the negative reciprocal of the other for the two to be parallel. C. The slopes of one line must equal the negative slope of the other for the two to be perpendicular. D. If the slopes are identical, as long as the intercepts are not equal, the lines are parallel.