How to enable listbox items based on another listbox selected item in WPF using MVVM?

Hi EveryOne,

I need to enable listbox items (consists of RadioButtons) based on another listbox selected item using MVVM.

It consists of seven to eight groups different groups. Any one help me to solve the problem?

ListBox 1:

           Fruits,

  Vegetables,

ListBox 2:

             Apple,Orange,Banana,Guva     ---> It should only enable when Fruits is selected.

             Carrot,Brinjal,Potato                ----> It should only enable when Vegetables is selected.

Thanks In Advance,

M.Reegan.