1. Both the dot product and cross product of two vectors A and B is zero, when:

(A) vector A and B are parallel to each other

(B) vector A and B are antiparallel

(C) A and B are perpendicular to each other

D) Either the vector is zero

Dear student....Answer should be (D) because cross product is zero only when the two vectors are parallel or antiparallel and dot product is zero only when the two vectors are perpenducular to each other.So , if Either the vector is zero then dot and cross product would be zero.....With Regards ....Mahima....(askIITians Forum Expert)