An archaeologist is dating several recently uncovered sites. She estimates that the site featuring a post-and-lintel design is older than the site featuring corbelled arches. Why might she have reached this conclusion? The corbelled arch did not become common until the first century C. E.
The post-and-lintel design was discontinued at the end of the Neolithic Era.
The corbelled arch required more advanced knowledge to create than the post-and-lintel design.
The post-and-lintel design did not require slave labor, unlike the corbelled arch.