Based on the dot plots below, witch of the following is a true statement?

I would say it's A because set B has 12 dots and set A has only 11.

The answer is a because 
set a has 11 dots:
20 has 1 dot
30 has 3 dots
40 has 2 dots
50 has 4 dots
60 has 1 dot
Total set A has 11 dots
1+3=4
4+2=6
6+2=10
10+1=11

Set B has 12 dots:
10 has 1 dots
20 has 3 dots
30 has 4 dots
40 has 2 dots
50 has 1 dot
60 has 1 dot
Total set B has 12 dots

It comes out of vehicles which pollutes the air

1.5 pounds because you put 9over 6 and then divide by 6