I believe that hair and limbs are homology because all mammals have hair and similar limb structure. Hair loss and social behavior on the other hand are homolasy because not all mammals have them. Homology is the similar traits due to common ancestry while homoplasy is similar traits for other reasons other than common ancestry.
He was one of the first scientists to understand that new scientific information comes from repeated experiments, and one of the first to incorporate math and science together. He revolutionized the method research was obtained by scientists.
The correct answer would be the last one: "evolved from past organisms." This theory basically just states that all living organisms evolved from a single common ancestor. Hope this helped! :)
