Which of the following is not essential for the 3 vectors to produce 0 resultant?
a) they should be in the same plane
b) It should be possible to represent them by the three sides of a triangle taken in order
c) They should act along the sides of a parallelogram
d) the resultant of any 2 vectors should be equal and opposite to the 3rd vector

a) That is required. If they are not, you'll find that there will always be a resultant.

b) That too is true, the triangle will therefore mean that the resultant is zero.

c) Not necessarily (anyway, I don't quite understand what that is trying to say)

d) That is true. The vectors should cancel each other, and to do that, a resultant of two of them should be equal and opposite to the last vector.

So, can you find the answer? :rolleyes:

Hope it helped! :)