SAN FRANCISCO (Bloomberg) - Apple Inc. will offer all music sold through its iTunes music store without copy protection and will introduce variable pricing for tracks. Songs will cost 69 cents, 99 cents and $1.29 starting in April, with most albums priced at $9.99, Apple marketing head Phil Schiller said yesterday at the Macworld conference in San Francisco. About eight million songs will be offered without copy-protection software as part of the iTunes Plus service starting yesterday, Apple said.