The diameter of a fly wheel is R. Its coefficient of linear expansion is $\mathrm{\alpha }$ . If its temperature is increased by $∆\mathrm{T}$ the percentage increase in its moment of inertia is

• A

  $200\times \mathrm{\alpha }\times \mathrm{\Delta T}$

• B

  $100\times \mathrm{\alpha }\times \mathrm{\Delta T}$

• C

  $50\times \mathrm{\alpha }\times \mathrm{\Delta T}$

• D

  $150\times \mathrm{\alpha }\times \mathrm{\Delta T}$