The correct response is All of the above.
The U.S. Copyright Act of 1976 did indeed:
- Extend copyright protection to the life of the author plus 50 years (this was later changed to life of the author plus 70 years with the Copyright Term Extension Act of 1998).
- Establish the doctrine of fair use, allowing limited use of copyrighted material without requiring permission from the rights holders.
- Establish the first sale doctrine, which permits the owner of a copyrighted item to sell or lend their copy without the permission of the copyright owner.
Thus, all the listed options were enacted by the U.S. Copyright Act of 1976.