D. The Speaker of the House.
While technically it would be the Vice President, he does not usually spend anytime at the Capitol, so it would be the speaker.
The attack on Fort Sumter, April 13th, 1861 culminates in the war led by the conflicts and tensions in the South, more specifically with the surrender of General Robert Anderson that set defense in Charleston Harbor in South Carolina. The fort took fire from artillery and bombardments by the Confederate State armies. The Fort couldn't stand long a defense, so it surrendered shortly after in April 1861 eventually leading to the formal declaration of war between the States in the North, loyal to the Constitution, and the southern states.. which were advocating for the split.
Nixon - vietnamization makes no sense because Nixon wasn't president until the 80's
<span>The argument can be made with substantial evidence that he was correct. Consider the entire history of the Cold War. A shorter study would be the Soviet invasions of Czechoslovakia and Afghanistan. Had either nation had strong, organized militaries, the USSR would likely never have crossed the borders.</span>