OFFICIAL ANSWER: E

Not sure how a choice with " greater eruption" be an answer.bit perplexed to what is being compared

gocoder wrote:Not sure how a choice with " greater eruption" be an answer.bit perplexed to what is being compared

In two letters to the historian Tacitus � Prepositional phrase followed by a comma � Modifies the whole action = wrote the only eyewitness account of the greater eruption of Vesuvius.

I think there was a typo....should be "great" instead of "greater" in option E since there is no real comparison going on.

Cthulu wrote:I think there was a typo....should be "great" instead of "greater" in option E since there is no real comparison going on.

Corrected!

The nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius in the two letters to the historian Tacitus.

clause + COMMA +"preposition phrase"
then the preposition phrase will act as a adverbial modifier.

(A) The nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius in the two letters to the historian Tacitus
bold phase is acting as adjective modifier and indicate that eruption occur in the letter - incorrect

(B) To the historian Tacitus, the nephew of Pliny the Elder wrote two letters, being the only eyewitness accounts of the great eruption of Vesuvius.
being is modifying nephew; intended meaning is not clear

(C) The only eyewitness account is in two letters by the nephew of Pliny the Elder writing to the historian an account of the great eruption of Vesuvius.

(D) Writing the only eyewitness account, Pliny the Elder's nephew accounted for the great eruption of Vesuvius in two letters to the historian Tacitus.
accounted for : cause of
nephew was not the cause of eruptions

(E) In two letters to the historian Tacitus, the nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius.
clear and concise