Question #N110

In 1985, the United States Congress passed legislation that would give the United States Postal Service the ability to deliver mail to addresses in the Caribbean. The Postal Serviceā€™s expansion, however, faced several challenges. One of the most important issues was the difficulty of convincing Caribbean nations that the Postal Service could provide them with a reliable and efficient service.

Which choice best combines the sentences at the underlined portion to maintain the style and tone of the passage?
A. The Postal Serviceā€™s expansion, however, faced several challenges, one of the most important being the difficulty of convincing Caribbean nations that the Postal Service could provide them with a reliable and efficient service.
B. The Postal Serviceā€™s expansion, however, faced several challenges; one of the most important issues being the difficulty of convincing Caribbean nations that the Postal Service could provide them with a reliable and efficient service.
C. The Postal Serviceā€™s expansion, however, faced several challenges, the difficulty of convincing Caribbean nations that the Postal Service could provide them with a reliable and efficient service, being one of the most important.
D. The Postal Serviceā€™s expansion, however, faced several challenges because of the difficulty of convincing Caribbean nations that the Postal Service could provide them with a reliable and efficient service.