Solution: Area of a period: π(4r? -r？ )=3πr？ ;

Area of comma: π×4r? ÷2=2πr？ ;

Question mark area:

3 /4 π(4r？ -r？ )+πr？ = 13 /4 πr？ ;

because

13 /4 πr？ The biggest, so the paint of the question mark is much used.

So the answer is: question mark.

This should be understandable.