D. keeps on
Feedback let out - 1. to make a loud sound 2. to loosen a piece of clothing 3. to take money from somebody for a rent. 4. to set somebody free.
keep on - to continue.
go off - 1.to explode 2. to make a loud sound 3. to stop liking 4. to stop functionate 5. to spoil.
give up - to stop doing something, especially if you do it on regular basis