Which of the following inventions of the 1950s made other inventions possible?

You didn't give us choices, but I suspect the answer you're looking for is:

the transistor

John Bardeen, Walter Brattain, and William Shockley were awarded the Nobel Prize in Physics in 1956 for the invention of the transistor. (It might be noted, however, that there was some friction between Schockley and the other two members of the Bell Labs' team, Brattain and Bardeen.) A 2007 article in Computerworld magazine calls the transistor "the single most important invention of the 20th century." In addition to its early uses, making transistor radios and car radios possible, transistors have become the key component to all types of electronic devices. The transistor also functioned as "the building block for the processor," according to Computerworld.

he believed that strong monarchies would lead to social and political stability.

i really do want to but i just don't know it i'm so sorry : (