The Chinese began using flags more than 3,000 years ago. They made flags from silk. Which sentence combines the two sentences using an adjective clause that functions as part of the subject?

The Chinese used flags, made with silk over 3,000 years ago.
Making flags from silk, the Chinese began using flags more than 3,000 years ago.
The Chinese, who made flags from silk, began using them more than 3,000 years ago.
The Chinese began using flags more than 3,000 years ago, and they made flags from silk.