What are the correct half reactions for the following reaction: Cu2+ + Mg -> Cu + Mg2+A. Mg+2e−→Mg2+ Cu2+→Cu+2e−B. Mg+e−→Mg+ Cu+→Cu+e−C. Mg→Mg2++2e− Cu2++2e−→CuD. Mg→Mg++e− Cu++e−→Cu