Which sentence BEST follows the guideline above?

He pursued his inquiry farther by contacting not only the city council but the mayor herself.

Though her class on genetics ended, she decided to study the topic farther on her own.

Eduardo drove further than Jeremy did, but they arrived at the party at the same time.

Janessa contemplated the mystery further, determined to be the one to solve it.

Janessa contemplated the mystery further, determined to be the one to solve it.