Answer:
I think B, AC = 5
Explanation:
You can see that the shape, DEF and ABC, both hav a number at the bottom. So We know that there is a scale factor of 2, because 6÷3 is 2. So, if we wanna know what AC is we can divide 10, from DEF, by two, we get 5. So, AC is equal to 5. :)