Question: What is a compilation album of previously unreleased songs and alternate takes recorded 1969–1980 by American singer-songwriter, who was one of the most popular acoustic artists of the decade and one of its best-selling artists?
Sentence (from "John Denver"): After traveling and living in numerous locations while growing up in his military family, Denver began his music career with folk music groups during the late 1960s.
Relevant evidence: No