Who sang the harmony on 5th Dimension by The Byrds?

The harmony on "5D (Fifth Dimension)" by The Byrds was primarily sung by Roger McGuinn, David Crosby, and Chris Hillman. The Byrds were known for their intricate vocal harmonies, which played a significant role in their sound. Crosby's distinctive voice contributed to the group's signature harmonies, enhancing the song's psychedelic feel.