How does an application become ‘amended’?

MPEP 203.03 defines an ‘amended’ application as:

An ‘amended’ nonprovisional application is one that having been acted on by the examiner, has in turn been acted on by the applicant in reply to the examiner’s action. The applicant’s reply may be confined to an election, a traverse of the action taken by the examiner or may include an amendment of the application.

In essence, an application becomes ‘amended’ when the applicant responds to an examiner’s action, whether through election, traversal, or by submitting amendments to the application.