Answer: Magnesium
Explanation:
Galvanic cell is a device which is used for the conversion of the chemical energy produces in a redox reaction into the electrical energy.
The standard reduction potential for magnesium and zinc are as follows:
Reduction takes place easily if the standard reduction potential is higher (positive) and oxidation takes place easily if the standard reduction potential is less (more negative).
Here Mg undergoes oxidation by loss of electrons, thus act as anode. Zinc undergoes reduction by gain of electrons and thus act as cathode.
Thus magnesium gets oxidized.