Build your character thoughtfully and painstakingly upon these precepts, and by and by, when you have got it built, you will be surprised and gratified to see how nicely and sharply it resembles everybody else's, what does this mean?

This means that if young people want to establish a good character, they must follow their own thoughts and desires, otherwise, they will be just like all other adults.

This is because Twain believes that society is not pleasant and if young people follow what that society determines as correct, they will become adults who will form another society exactly the same, for that reason, rebellion, new thinking, and the courage to follow their own thoughts were needed.

More information about Mark Twain at the link:

link

This quote comes from the text "Advice to Youth" by Mark Twain. In this text, the author claims that he is giving advice to young people. However, the advice that he provides is ironic, and is instead intended to express the idea that a free mind and a rebellious nature are better for youth than a desire to listen to the advice of others. Twain ends with these lines, and the meaning that he wants to convey is that, if you base your life listening to the advice of others, you will end up with a character that is simply the same as that of everyone else.

i cannot see any of the options