question_answer

Let a, b, c be distinct non-negative numbers. If the vectors and \[a\hat{i}+a\hat{j}+c\hat{k},\] \[\hat{i}+\hat{k}\] and  \[c\hat{i}+c\hat{j}+b\hat{k}\] lie in a plane, then c is

A)  the Arithmetic Mean of a and b

B)  the Geometric Mean of a and b

C)  the Harmonic Mean of a and b

D)  equal to zero

E)  None of these