''He now had to make a decision, a choice between two dreams.'' is the sentence that is showing how the actions of a character develop the theme since after this sentence readers will expect and want to know what will happen. They know that the character must decide and do something about his problem.
B is an incorrect answer because in this sentence it says that the character will not make that decision today so the readers will have a feeling like the character would not do anything about it.
C and D are blocking the theme, they are not developing it since the character in both sentences is wanting to forget about the situation.
