If two people have a common goal then by working together they can accomplish that goal.
This justifies what answer for what question? Q & A: 
If two people have a common goal how can they accomplish that goal?
Options:
- agree with each other
- work together
- make love
- have fun
- shake hands
work together
If two people have a common goal then by working together they can accomplish that goal.
This justifies what answer for what question? Q & A: 
user
If two people have a common goal how can they accomplish that goal?
Options:
- agree with each other
- work together
- make love
- have fun
- shake hands
work together
assistant
If two people have a common goal then by working together they can accomplish that goal.
This justifies what answer for what question? Q & A: 
If two people have a common goal how can they accomplish that goal?
Options:
- agree with each other
- work together
- make love
- have fun
- shake hands
work together