I have a class A with a public method in C#. I want to allow access to this method to only class B. Is this possible?

UPDATE:

This is what i'd like to do:

public class Category
{
    public int NumberOfInactiveProducts {get;}
    public IList<Product> Products {get;set;}

    public void ProcessInactiveProduct()
    {
        // do things...

        NumberOfInactiveProducts++;
    }
}

public class Product
{
    public bool Inactive {get;}
    public Category Category {get;set;}

    public void SetInactive()
    {
        this.Inactive= true;
        Category.ProcessInactiveProduct();
    }
}

I'd like other programmers to do:

var prod = Repository.Get<Product>(id);
prod.SetInactive();

I'd like to make sure they don't call ProcessInactiveProduct manually:

var prod = Repository.Get<Product>(id);
prod.SetInactive();
prod.Category.ProcessInactiveProduct();

I want to allow access of Category.ProcessInactiveProduct to only class Product. Other classes shouldn't be able to call Category.ProcessInactiveProduct.