Correct answer would be C
Answer: It indicates that wagon consisting the letter X is the last wagon of the train. It easily alerts the railway officials so that they can save from the accident.
Explanation:
The major difference was the decision on actually becoming a knight. For people who could become knights (because their father was one), it was optional to become a knight. For a samuari, this option didn't come into play - they had to become one if their father was a samurai.
