If A(x1,y1,z1) and B(x2,y2,z2) are two points in space, which of the following expressions represents the vector AB in component form?
(a) 2x1+x2i^+2y1+y2j^+2z1+z2k^
(b) (x2−x1)i^+(y2−y1)j^+(z2−z1)k^
(c) (x1−x2)i^+(y1−y2)j^+(z1−z2)k^
(d) (x1+x2)i^+(y1+y2)j^+(z1+z2)k^