**The correct option is (3) 4.**

**Explanation:**

The required number of vectors is 4. suppose A,B,C, D are four vectors and no three of them are coplaner. if the resultant of A and B be X, and resultant of C and D be Y. if X, and Y be equal in magnitude but in opposing directions, that's the only way the resultant of A, B, C, D be zero, without any three of them being in the same plane.