Answer:
A.It was the most vital transportation hub for the capital.
Step-by-step explanation:
The city of Petersburg was a railroad hub that supplied Richmond with supplies. For this reason, this city was so important to the capital Richmond.
Knowing that a direct attack on Richmond would be disastrous, the union moved its forces southward south of the James River to attack Petersburg, a railroad hub that supplied Richmond with supplies. Instead of a direct attack, the union chose to surround Petersburg and slowly stagnate it with the lack of supplies to Richmond.