In accordance with the federal regulation in 33CFR Subchapter O, which discharge of oil or oily mixture to sea is permissible?

Correct Answer: Option C — When the discharge is necessary to for the purpose of securing the safety of a ship or saving life at sea.

33 CFR 151.10(b) prohibits the discharge of oil into the sea, except when necessary for the purpose of securing the safety of a ship or saving life at sea. This exception recognizes that human safety and vessel integrity take precedence over environmental protection during extreme emergency situations.