I like 3 because that sort of story will show that you have some resilience, grit, and an ability to course correct after you’ve made a mistake while at the same time giving yourself a position unique to you. The 2 and 4 just seem a little too on the nose for a medical school applicant as to be banal, given that most of us have experienced those things. Number 1 is also still about school, which is fine, but I honestly think these essays should be focused on other aspects of your life to show that you are a multi-dimensional person. Be as detailed as you can without being overly verbose, and I think you will have a good essay here.