The grid pattern helped and still helps encourage people to do what?
选项：

A:It encourages people to find a place and never move from there.
B:It encourages people to move west historically because the grid provides a pattern for them to follow.
C:It encourages people to buy land in the center of the grid, because this is the most important place.
D:It encourages people to move to the cities so they are closer to schools and shopping areas.