The distance between the earth and the moon is about 40,000km, which is:
![4,000,000,000\operatorname{cm}]()
Now, given that a dollar bill is about 15cm long, we can write:
![\frac{4,000,000,000\operatorname{cm}}{15\operatorname{cm}}=266,666,667]()
As you can see, we would need about 266,666,667 dollar bills to lay end to end stretch the 40000 km distance from earth to the moon. Thus, 9 million dolar bills is way too small.
If you see, if only 9 million dollars were needed, each dollar bill would have to be about 4 meters long. So, the correct answer is D