Answer:
( At that very moment Ivan Ilyich fell through and caught sight of the light, and it was revealed to him that though his life had not been what it should have been, this could still be rectified.)
Explanation:
The answer shows that Ivan Ilyich finally understands the cause of his suffering. I think that because it says "and it was revealed to him that though his life had not been what it should have been, this could still be rectified.", and I think that shows when he realises it.