Concept:This question tests the correct phrase used to cite a source or legend.
Explanation:The blank introduces the source of the information: an old legend.
"According to" means "as stated by" or "as reported by".
So, "According to an old legend" means "as the old legend says".
"Due to" shows cause, "In the event of" means if something happens, and "In reference to" means regarding.
None of these fit the source-citing meaning.
Therefore, "According to" is the correct phrase.
Answer:According to an old legend, King Shirham lived in India.