What is the correct way to rewrite sentence 3?

a. people, continue to think of intriguing new theories about how the giant mysterious monument was built.

b. people continue to think of intriguing new theories about how the giant, mysterious monument was built.

c. people continue to think, of new intriguing theories about how the giant mysterious monument was built.

d. people continue to think of new, intriguing theories, about how the giant, mysterious monument was built.