In the 1970s, the supply of gas was affected by price controls imposed by the Nixon administration and then by an oil embargo by Arab members of the Organization of Petroleum Exporting Countries (OPEC).
As a political move aimed at pleasing voters, President Richard Nixon announced in 1971 (prior to his reelection campaign of 1972), "I am today ordering a freeze on all prices and wages throughout the United States.” The wage and price controls the Nixon administration sought to put in place interfered with natural market forces and oil supplies were reduced. That problem was magnified in 1973 when oil exporting countries in the Arab world imposed an embargo on supplies to the United States due to US support of Israel in a war that Israel was fighting against a coalition of Arab states.
Both factors -- lingering efforts at price controls and continued control of the oil and gas market by OPEC nations -- played into the long lines at gas pumps seen in America in the 1970s.
His goal was to expand his empire and gain more prestige among nations
I believe THE ANSWER IS A,D
Black holes themselves can not be seen, nor do they leave trails (since emptiness does not have to be caused by a black hole), but there is evidence for black holes: scientists can see the effects of their gravity on nearby stars. The answer is B.