In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be:

Y forms CCP lattice so effective atoms of Y unit cell =4

Number of tetrahedral voids 2 x 4 = 8

Effective atoms of X = 8 x 2/3 = 16/3

Now formula -

X_16/3Y₄

X₄Y₃

The correct option is is (A) X₄Y₃