Answer:
G; Definition 2
Step-by-step explanation:
You gave me this sentence,
"After leaving for sanctuaries of high school and university and going out into the workplace, I entered the real messy world where my progress was not measured by end-of-term exam of validated by my prowess on a sports field. My life losses began to exceed my success, and I began to think that there must be more to life than winning."
I believe that the "of" before validated was supposed to be "or", and assuming that, the second definition is correct since the writers progress was being confirmed by their prowess on a sports field.