Who earns it for them. Why do Mormons call these works that they do on behalf of others, "Saving Works?"
From the above link at lds.org
In His mercy and infinite love, the Lord has prepared a way for them to gain a testimony of the gospel and receive the saving ordinances of the priesthood. Our effort approaches the spirit of the Savior's atoning sacrifice—we perform a saving work for others that they cannot do for themselves.