The statement tells us two important things:
1. For every 12 plums, 2 have worms.
2. Jamie has picked 56 plums
For this, we know that the probability that it has worms is 2/12 and that the set of total plums is 56 so of those 56 plums we can know how many have worms by multiplying them by the probability that this event could happen.
In conclusion, approximately 9 plums have worms, the answer is the B option