There are not too many things that are more insoluble than AgCl. When you actually do this experiment, virtually all of the AgCl sinks to the bottom of the test tube (or whatever container you are doing it in). The CuCl2 is very soluble. It is a gorgeous Forest Green with a very slightly blue tinge so you can tell that you are successful.
CuCl2 is very soluble.
That makes A incorrect.
AgCl is really insoluble
Looks like B is the answer.
C is just wrong. No complex is formed. The equation is a double replacement.
AgNO3 + HCl ====> AgCl(s) + HNO3 Not a good example but it is correct.
Cu(NO3)2 + 2HCl ===> CuCl2 + 2HNO3
D is not true. Ag will react with the HCl That's how you get AgCl going to the bottom.
E A double replacement need not transfer electrons. In this case it does not. E is incorrect.