Answer: B.
Explanation: When we talk about expanded form we are talking expanded right?
So, you wouldn't want to combine the 100,000,000 and the 20,000,000 and the 4,000,000 you want them expanded out just like I had them, so A is out.
Next we have C. We are talking about thousands here so the 750 doesn't make sense.
Finally, we have D. with expanded form we only want addition no multiplication so for that reason D. is out
B. Looks good to me they expanded everything out no multiplication, no numbers combined (eg. 124,000) so for that reason B. is the answer!
If you need any further instruction or help let me know!