EXTREMELY DIFFICULT ELECTROCHEMISTRY.. Can YOU do it?

Question

I honestly have no idea whats going on in this question... but here it is.
zn(s)+cu+2->zn+2+cu(s)
an electrolytic cell based on the reaction represented aboce was constructed from zn and cu half-cells. The observed voltage was found to be 1.00volts instead of standard cell potential, E0, of 1.10volts. which of the following could correctly account for this observation?
1. the cu electrode was larger than the zinc electrode
2. the zn+2 electrolyte was zn(no3)2, while the cu+2, electrolyte was cuso4
3. the zn solution was more concentrated than cu solution
4. the solution in the half cells had different volumes
5. the salt bridge contained kcl as the electrolyte..

PS. cu+2 OR zn+2 means that its an ion with 2+ charge

THANK YOU

Answer 1

Answer 3. Altering the concentration alters the standard electrode potential.