Is widely believed that when President Eisenhower signed a bill to create a national interstate highway system in 1956, he did it for what primary purpose?
A) to allow people to move to the western U.S. more easily
B) to allow people in suburban areas to enter big cities more quickly
C) to force southern states receiving federal funds to end segregation
D) to provide the means to transport military aid more quickly in the event of a national military crisis