Need help with #16 please!! Thank you everyone :)

Answer:
D.25cm
Explanation:
Just use a ratio between the two cells...
If... 12 micrometres = 15 cm
then.. 20 micrometres = ?
Then you divide....20 ÷ 12 = 5/3
then you multiply.... 5/3 × 15
Then you obtain 25cm