Answer:
B. If people do good things for others, they believe good things will happen to them.
What is karma?
What you are now is a consequence of what you were yesterday.
This is karma.
All your life, all your actions, all your thoughts, all your decisions since the first day of your life have led you to become what you are right now.
The apologies you forgot to ask, define the relationship you have with this person today.
The exercises you did all summer difine your health condition today.
The cleaning you did today is the reason why you can relax in a clean house now.
Karma acknowledges that whether you live in heaven or in hell today is a consequence of your past actions and thoughts.
So, if you want a better tomorrow, start today.
There is no need to go religious on this one.
Usually it is misunderstood as a mystic cosmic force that guides the world and, for a few unkonwn reason, directs back all you did to the world.
that is a misconception, a metaphor at its best.