The answer to this question is actually just simple arithmetic. At the end of the first round, Katie and Jenny will have 100 points each. In the second round, Katie and Jenny will have 200 points and 300 points respectively. At the third round, Katie and Jenny will both have 400 points. At the fourth round, Katie and Jenny will have 800 and 600 points respectively. So the turn at which Katie will have more points than Jenny is the fourth round since Katie has 800 and Jenny has 600.
Area of the large semicircle
Area of the small semicircle
Area of the figure
B
is the right answer.
hope i helped
