It looks good, but is there better?

Oliver Cromwell, an English military and political leader in the 17th century, said, "He who stops being better stops being good."

At the bridge table, if you spot what looks like a good line of declarer-play or defense, pause to see if there is something better.

How is that relevant in today's deal? South is in four hearts. West leads the diamond two. How should East defend?