I would answer nesting dolls.
*You control your own destiny.*
Two lines of the poem directly support this claim. They are...
"I am the master of my fate:
I am the captain of my soul."
Meaning that the ultimate determining factor is you. Everyone is granted a choice, fate and destiny do not control you, because everyone has free-will.
Answer:
Buck is a good leader and had good similar leadership qualities like his predecessor.
This is because he made sure everything was in order. He also showed that he had the strength and was a good motivator of the people. He was able to persevere different conditions while leading the group of people.