Which of the following is a galvanic cell? A. Silver (Ag) oxidized, aluminum (AI) reduced
B. Copper (Cu) oxidized, aluminum (Al) reduced
C. Aluminum (Al) oxidized, zinc (Zn) reduced
D. Aluminum (Al) oxidized, sodium (Na) reduced

C. Aluminum (Al) oxidized, zinc (Zn) reduced

Given

Metals that undergo oxidation and reduction

Required

A galvanic cell

Solution

The condition for voltaic cells is that they can react spontaneously, indicated by a positive cell potential.

or:  

E ° cell = E ° reduction-E ° oxidation  

For the reaction to occur spontaneously (so that it E cell is positive), the  E° anode must be less than the E°cathode

If we look at the voltaic series:

Li-K-Ba-Ca-Na-Mg-Al-Mn- (H2O) -Zn-Cr-Fe-Cd-Co-Ni-Sn-Pb- (H) -Cu-Hg-Ag-Pt-Au

The standard potential value(E°) from left to right in the voltaic series will be greater, so that the metal undergoing an oxidation reaction (acting as an anode) must be located to the left of the reduced metal (as a cathode)

From the available answer choices, oxidized Al (anode) and reduced Zn (cathode) are voltaic/galvanic cells.