If the co-ordinates of the points A, B, C, D be (1, 2, 3), (4, 5, 7), (-4, 3, -6) and (2, 9, 2) respectively, then the angle between the lines AB and CD is

The correct option is D

None of these

Here, d.r.'s of line AB and CD are 3, 3, 4 and 6, 6, 8 respectively.
$\therefore \theta =co{s}^{-1}\left[\frac{\left(3\right)\left(6\right)+\left(3\right)\left(6\right)+\left(4\right)\left(8\right)}{\sqrt{34}.\sqrt{136}}\right]=co{s}^{-1}\left[\frac{68}{2\times 34}\right]=0^{\circ }$