Question 1 is D.<em> </em>
It's not clear that the science class is a good sample of the school as a whole. It may be an elective or for a particular grade, making it a biased sample.
For Question 2 I'll try to create the histogram from your description.
N TOP BOTTOM
9 3 3
10 5 4
11 2 3
If that's accurate the BOTTOM, B, group has longer arms, due to a single person measuring 11 instead of 10.
Neither B or D is really a good answer making me think I transcribed the table incorrectly. I'd guess D