Answer:
B 1.33 x 10^6
Step-by-step explanation:
first before calculating any magnification, you need to make sure all units are the same
you can convert 7.5nm to mm which is basically
7.5 x 10^-6
now all values are in mm, we can calculate magnification:

image size is the length in the diagram = 10mm

If you put this into a calculator you'll get the answer:
1.33 x 10^6 which is option B
Note that magnification has no units as they are canceled off.