In order to interprete literature the cultural context is fundamental because it is likely to have influence on the narrative, that is, the story may be based on tipical problems or events which took place at the time the author wrote the it, such as a revolution or a war. Besides, the biography of the author may also play a key role to interprete a story since certain authors tend to write stories invoking personal experiences, such as discrimination because of racism, for example. Finally, quotes from the text are much more significant, because they can be the own words of the characters, or the author himself, so they should be analized aiming to undestand the intention of the author with his story.
So, I must say that your own comment on the text is the option which is not an acceptable form to evidence yout interpretation.
It would be his hunger, thirst, and suffocation in the train car. The other options are internal conflicts because they are occurring inside his head and are emotions or thoughts.
Macbeth made the mistakes. First, he tries to back down when he has second thoughts. Second, He forgets to plant the knives on the guards. Lady Macbeth steps in to fix the mistakes. She gets Macbeth to go through with the murder and plants the bloody knives on the guards after Macbeth refuses to re-enter Duncan's room.
