What obstacles to road building did the romans faced

Well they had obstacles of mostly barbarians or clans attacking them. remember that during roman times clans were trying there hardest to pillage and destroy Rome.

Explanation:

The correct answer is D. The Nixon Doctrine was the policy that was an attempt by President Nixon to withdraw US soldiers from Vietnam.

Explanation:

The Nixon Doctrine was proposed at a press conference in Guam on July 25, 1969 by Richard Nixon. Nixon declared that the United States hoped from that moment on that its allies would take charge of their own military defense. The Doctrine was argued based on the search for peace through an association with American allies.

This was the first step of Vietnamization, which involved the withdrawal of the United States from the Vietnam War.