C. by explaining that all the birds came together for a contest.
Explanation:
<u>The purpose of a summary is tell the story in a shorter way. It should not eliminate important information, nor should it include unnecessary information. In this particular case, we should maintain the beginning of the story as the beginning of the summary. If we skip it, the story will not make sense. Everything that happens happens because of the contest between the birds. </u>Therefore, a summary of this story should begin with C. by explaining that all the birds came together for a contest.
