The most appropriate action for Ravi is:
Ravi should calculate his estimated balance due. He should then complete and file Form 4868, Application for Automatic Extension of Time To File U.S. Individual Income Tax Return, and include a payment for the estimated balance due no later than April 15th. After April 15th, he should file his return no later than the extension deadline of October 15th.
This option is the best because it allows Ravi to formally request an extension while also ensuring he pays any estimated taxes owed by the original deadline to avoid potential penalties and interest. Filing Form 4868 gives him until October 15th to actually submit his return, but he should still pay any estimated balance due by April 15th.