In 1913, Elmer McCollum helped discover which nutrient, needed for healthy eyes?

By law, which U.S. holiday falls on the fourth Thursday in November? By March 1781, all 13 states had approved which articles, America's first constitution? Which comic strip was created by Matt Groening before "The Simpsons"? Complete the title of Maurice Sendak's 1970 picture book: "In the ___ Kitchen." By mid-1990, all of Liberia except parts of which capital city was controlled by rival rebel groups? After defeating his brothers in a civil war, Mehmed I reunited which empire in 1413? Motorola's StarTAC, introduced in 1996, was an early flip-style version of what device? Which secretary of defense was kept in office by President Obama after serving under George W. Bush?