John,impersonating a Police Officer,goes to Martha's Home and Falsely Advises

John,impersonating a police officer,goes to Martha's home and falsely advises Martha that he has a search warrant.Martha allows John into the house.John then seizes Martha.He knocks her to the floor and attempts to sexually assault her.Martha is able to elude John's efforts and escapes unharmed.Of the following,the most serious offense John has committed is:

A) criminal trespass.
B) robbery.
C) home invasion.
D) burglary.