B - 10 pages
To find this, first convert 2.5 hours into minutes. You should get the answer of 150 minutes.
Then, you need to divide by 20, or the amount of minutes and pages conversion we are given. With that, you'll get 7.5 You'll then need to multiply 7.5 by 4/3, or 1.3, and get 9.75. You'll need to round that up to 10, aka B.
Hope this helps!