Which statement best describes the graphs of the lines y=-x-3 and y=x+6
A) They are the same line.
B) They are parallel lines.
C) They intersect at exactly one point.
D) They intersect at exactly two points.

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6