A circular disc `X` of radius `R` is made from an iron of thickness `t`, and another disc `Y` of radius `4R` is made from an iron plate of thickness `t//4`. Then the relation between the moment of mertia `I_(x)` and `I_(Y)` is :
A. `I_(y)=32 I_(x)`
B. `I_(y)=16 I_(x)`
C. `I_(y)=I_(x)`
D. `I_(y)=64I_(x)`