The reaction in a Daniell cell is:

• a$\ce{Zn + CuSO4 -> ZnSO4 + Cu}$
• b$\ce{Cu + ZnSO4 -> CuSO4 + Zn}$
• c$\ce{Zn + Cu -> ZnCu}$
• d$\ce{Zn + H2O -> ZnO + H2}$