There is more surface for nails to grip. thats the one for apex
The speaker is talking about the water. During winter, the water enters the cracks and freezes and expands. It breaks the stone and makes cracks and when the water melts the holes are bigger. What he is describing is mechanical weathering which is common in nature.
This is a part of his supreme ordeal. His return home is much broader and includes his supreme ordeal which is what you described in the question. He fought them because he wanted to stop them from taking his wife Penelope. This was during the competition where they had to prove themselves.
The answer is C. He hopes that Duncan will wake and prevent the murder