ForEach for Two List asp.net MVC

Question

I have two list and the list shows up when I selected a group
I have GrpA,GrpB,GrpC in a dropdown

When I select  GrpA or GrpB or GrpC  I want to show all the all the list<AppModule> with checkbox not check but when GrpA contains A,B,C I want them to be checked and the rest not checked 

        public List<AppModule> AppModules { get; set; }
        
        A,B,C,D,E,F,G(show the list with checkboxes beside them not checked)

      

        public List<AppModule> GroupModules { get; set; }
       A,B,C

Any help.Thanks John