The correct option is
C Dismount
“Get off” means to get down from, or to take something off something.
“Overcome” means to succeed in dealing with
“Find agreeable” means to find something that you can totally agree with and have the same opinion.
“Succeed” means to achieve the desired aim or result.
“Dismount” means to get off from a horse or bicycle, or remove something from its support.
“Set free” means to relieve someone who is trapped.
Hence option D is the correct answer as it is the correct meaning of the given phrase.