For the first time I saw him speaking so rudely to Ranjeet.

Answer: Option C

Rudely : in an offensive or bad-mannered way.
Softly : in a careful and gentle manner.
Gently : with a mild, kind, or tender manner.
Politely : in a respectful and considerate manner.
Slowly : at a slow speed; not quickly.

Antonym of Rudely is Politely