The answer is B.) a universal theme.
(Because you know, the word 'universal' is in there, which pretty much means its understood across the entire world.)
Also, it's not main idea because main ideas for things are like... different. For example, the Bible probably has a different main idea compared to a Thomas the Tank Engine book.
And personal symbols are well, personal. (Obviously.)
And context clues are clues that help you figure a message or something out, not the message itself. For example, if I say "I felt small compared to the mammoth house", you can assume 'mammoth' means 'large' due to the context clue of me feeling small.