The correct option is D 200√3
Area of circle =100π
πr2=100π
r2=100
r=10
Now, a regular hexagon is made up of 6 equilateral △s of equal areas. Now, height of equilateral △ is equal to radius of circle.Therefore, ar. of 1 equilateral △=12 x base x height
⇒√34a2=12∗a∗10⇒a=4∗102√3=20√33
Area of hexagon 6∗(√34a2)=6∗√34∗20√33∗20√33=200√3