The correct option is C disjoint
We have {x: x is an odd number} ={1,3,5,7,...} and {x: x is an even number} ={2,4,8,10,...}.
Since no element of the first set is an element of the second set and vice-versa, we have {x: x is an odd number} and {x: x is an even number} to be disjoint sets.