How can I group by a list of elements?

I run into this issue again and again: how can I group a list of objects by a containing list of other objects?

I have a list of objects of type A and each of these objects has an property (lets call it ListProp) which is a list also. ListProp has elements of the type B. There are multiple elements of type A with identically B-objects in ListProp, but the ListProp property reference differs from element to element. How can I group these A-objects the fastest way, where the B-objects in ListProp are identically?

Sample code:

class Program
{
    static void Main(string[] args)
    {
        var exampleList = new List<A>
        {
            // Should be in first group
            new A { ListProp = new List<B>
            {
                new B { Prop = new C { Number = 0 }},
                new B { Prop = new C { Number = 1 }}
            }},
            // Should be in first group
            new A { ListProp = new List<B>
            {
                new B { Prop = new C { Number = 0 }},
                new B { Prop = new C { Number = 1 }}
            }},
            // Should be in second group
            new A { ListProp = new List<B>
            {
                new B { Prop = new C { Number = 0 }},
                new B { Prop = new C { Number = 1 }},
                new B { Prop = new C { Number = 1 }}
            }},
            // Should be in third group
            new A { ListProp = new List<B>
            {
                new B { Prop = new C { Number = 0 }},
                new B { Prop = new C { Number = 0 }}
            }}
        };

        // Doesn't work because the reference of ListProp is always different
        var groupedExampleList = exampleList.GroupBy(x => x.ListProp);
    }
}

class C
{
    public int Number { get; set; }