H&K MP5 Sub-Machine Gun Test Quiz Questions

I am semi-retired and I am taking a self-passed and self-taught Armorers course and now I am on the H&K MP5 Sub-Machine Guns I hope to become a part-time light Gunsmith in the future.

There are over 60 quiz questions covering this firearm and I have answered most of them but during my study and research I am having some problems related to some of the following quiz questions. Either I am not sure of the correct answer or I have conflicting answers.

Can you help me determine the correct answers for these few 6 quiz questions?

Thanks for your help.

Note #19. The extractor is a pivoting type of extractor and it acts as its own spring. True or False.
a) True
b) False

Note #20. Unless you are trying to launch the butt stock across the room, what must you make sure of before removing the butt stock from the receiver?
a) Make sure that the bolt is open
b) Make sure that the bolt is closed
c) Make sure that the hammer is down
d) You need rockets to make the butt stock launch across the room

Note #21. What must come off of the gun before the bolt assembly can come out of the receiver?
a) The fore end
b) The butt stock
c) The front sight
d) The rear sight

Note #22. What holds the cap (located under the front sight) onto the gun?
a) A roll pin
b) It screws on (right hand thread)
c) It screws on (left hand thread)
d) A spring loaded plunger

Note #23. When disassembling the gun, the roll pin for the cocking handle should be driven from...
a) The top of the gun to the bottom
b) The bottom of the gun to the top

Note #24. When in working position, the paddle portion of the thumb release for the magazine should face towards the rear of the receiver. True or False.
a) True
b) False