Step 1 : Introduction to the question "Which of these U.S. presidents did not graduate from a U.S. military academy?"
...Many American presidents attended or graduated from U.S. military academies, most notably West Point and the U.S. Naval Academy. Ulysses S. Grant and Dwight D. Eisenhower were distinguished West Point graduates, while Jimmy Carter graduated from the Naval Academy. Herbert Hoover, however, had no military academy background at all—he earned a degree in geology from Stanford University and spent his early career as a mining engineer. His non-military academic path makes him the only correct choice among the options.
