I'm solving a single-choice question in the exam. The question has $4$ options: A,B,C,D. These are my steps:
$1$. I didn't understand any choice of the four, so I randomly selected one: A.
$2$. After $1$, I figured out that D is wrong, according to the conclusion of Monty Hall problem, I change my answer, randomly chose one between B and C, suppose B. I should change, right? :) to increase probability from $1/4$ to $3/8$.
$3$. After $2$, I figured out that C is wrong, so should I change back to A? And what's the probability of each one? What if I figured out A instead of C wrong?