If you meant to say reciprocate it means to respond to (a gesture or action) by making a corresponding action.
Because is the correct answer. The word because is connecting the two statements together and explaining how they finished their work.
This is not always true. Planned action such as a premeditated murder has a negative consequence. While, on the other hand, a planned action such as doing your homework first thing when you get home, can have a positive consequence such as having more free time to do what you wish.
Answer:
To not fail english
(ignore this part is asked for 20 characters)
