Hello, I hope you are well!
I don't quite understand how the OA is correct.
He is taller than she - this is definitely correct because we can omit "is" in "she is" but the sentence in question doesn't have the same format. If it said that - people who are wealthier, better educated and more polished than he - it would definitely work. But the statement has no verb, it says there are the world is dominated by people wealthier, better educated and more polished than him. Please advise.