See the issue is that I don't even know why SQL Server uses this Index? This Index is useless in this situation because column C1 is ID column which is not in the query.
"He who learns for the sake of haughtiness, dies ignorant. He who learns only to talk, rather than to act, dies a hyprocite. He who learns for the mere sake of debating, dies irreligious. He who learns only to accumulate wealth, dies an atheist. And he who learns for the sake of action, dies a mystic."[/i]