Advertisement: At most jewelry stores, the person assessing the diamond is the person selling it so you can see why an assessor might say that a diamond is of higher quality than it really is. But because all diamonds sold at Gem World are certified in writing, you're assured of a fair price when purchasing a diamond from Gem World.

The reasoning in the advertisement would be most strengthened if which one of the following were true?
A. Many jewelry stores other than Gem World also provide written certification of the quality of their diamonds.
B. The certifications of diamonds at Gem World are written by people with years of experience in appraising gems.
C. The diamonds sold at Gem World are generally of higher quality than those sold at other jewelry stores.
D. The diamond market is so volatile that prices of the most expensive diamonds can change by hundreds of dollars
from one day to the next.
E. The written certifications of diamonds at Gem World are provided by an independent company of gem specialists.

[spoiler]I was stuck between B and E. OA-E
Please explain B and E in detail why is E preferred over B?[/spoiler]