Answer: A
E=E∘(AgX+/Ag)+0.0591log[AgX+]. Precipitation of AgCl removes AgX+ from solution, so log[AgX+] becomes more negative and E decreases. The electrode now behaves as a Ag ∣ AgCl ∣ ClX− electrode with E∘=0.22 V, well below 0.80 V, but it is not zero.