i am fairly sure 2 was A as salt water contains ions which are free charge carriers which accelerate the rate of corrosion. Cold-rolled brass would not corrode from just the "stress factor" if it were in air therefore by placing it in a solution of electrolytes will accelerate the rate of corrosion as the electrons can free move within the metal forcing the metals in the alloy to establish an electrolytic/galvanic cell and corrode.