Petersburg is really crucial for the victory because it's the main point for the Confederate's supply line.
By winning the war of Petersburg, the union managed to cut off food and ammo supplies for other soldiers in another battlefront which eventually caused the Confederate army to start falling like dominos.
The New Jersey Plan would most likely be supported by "<span>(B) states with small populations," since it called for representation in Congress to be determined by a set number of representatives per state, instead of having it be determined by population size. </span>