How to solve this logarithmic word problem? On earthquakes. Correct me!?

The Richter scale of earthquake measurement is a 'logarithmic' scale

i.e. Each graduation on the Richter scale produces an earthquake of ten times the magnitude of the preceding one.

so, earthquake B is ten times stronger than earthquake A.

*Note* If there was another earthquake that measured 4.6 on the Richter scale, this would be ten times stronger than earthquake B, and 10 x 10 = 100 times stronger than earthquake A!!

Here is a site that will help further:

http://en.wikipedia.org/wiki/Richter_magnitude_scale

:)>

I think the answer is d, because the Richter magnitude scale is a base-10 logarithmic scale. Which means that an earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger than one that measures 4.0 (or the 5.0 is 10 times stronger then the 4.0 )