Which is the best explanation of how the main character helps to
reveal the theme?

ill need more info in order to answer yer ?

tom robinson he was a black man that was accused of raping caucasian woman, and an idealistic lawyer offers to defend him. which makes nobody believe in the innocence of a negro.

in the 1890s, southern states enacted a new form of black codes, called “jim crow” laws. these laws made it illegal for blacks and whites to share public facilities. this meant that blacks and whites had to use separate schools, hospitals, libraries, restaurants, hotels, bathrooms, and drinking fountains.

explanation:

21 balloons is the story of professor william sherman's travels.

in 1883, he set off from san francisco for a balloon ride over the pacific and was found a month later floating with 21 balloons in the atlantic ocean. this seemed an astounding feat and everyone wanted to know what had happened.    

professor sherman was loyal, however, and said he would tell his tale first to the western american explorers club in san francisco, of which he was a member. this built up suspense for several chapters before he began to tell of the wonders of his adventures and the amazing island of krakatoa, an island which had just been blown up by a volcano.  

the residents of krakatoa are all millionaires who live under a "gourmet government" of their own devising. we get to see all the incredible adventures that creative people with unlimited resources would create according to the author.