JEE Math Practice Question

The outcome of each of 30 items was observed; 10 items gave an outcome $${1 \over 2}$$ – d each, 10 items gave outcome $${1 \over 2}$$ each and the remaining 10 items gave outcome $${1 \over 2}$$+ d each. If the variance of this outcome data is $${4 \over 3}$$ then |d| equals :

1. A.$${2 \over 3}$$
2. B.$${{\sqrt 5 } \over 2}$$
3. C.$${\sqrt 2 }$$
4. D.2