Understanding the argument -
Ancient Greek vase painting provides a consistent portrayal of satyrs (mythological part-goat, part-human creatures) as comic social creatures, fond of wine and given to excess. - Background info.
The statue known as the Barberini Faun is notably different in its depiction. - Fact.
Although scholars agree that the figure is a satyr, the only indication of its wilder, animal nature is a small tail. - Contrast.
Apart from this, the figure appears to be a calm, solemn, well-muscled man who is situated in obvious isolation from others. - further substantiating the contrast.
These facts suggest that the statue portrays not just any satyr, but the satyr that King Midas captured by drugging its drink with a sleeping potion. - Conclusion.
Which of the following, if true, would most strengthen the argument above?
Option Eliminatio - Strengthen
Who says that GMAT doesn't test vocabulary

Solemn means - not delighted, serious.
Temperate means - calm.
A. The location of the figure suggests that it is vulnerable to attack. - out of scope.
B. The satyr in the Midas myth is typically described as a serious and temperate creature. - matches with the description of the statue known as the Barberini Faun (BF). ok
C. Grapes and ivy around the figure's head indicate its association with wine. - this is typical of any satyrs. There is no specific linkage between BF and King Midas's myth. Distortion.
D. The depicted length of a satyr's tail did not always symbolize a satyr's tendency to excess. - weakener at best.
E. The Barberini Faun was discovered in the same area as a vase painted with a scene from the Midas myth. - may provide circumstantial evidence but not the direct link as provided by B related to the statue's characteristics.