Explanation:
To unpin this object you need to use "EXECUTE dbms_shared_pool.unkeep" command.
Incorrect Answers:

1: This command just will flush the shared pool: all space in the shared pool is then freed temporarily for new statements to parse, which temporarily reduces performance for other statements running on the system.
2: There is no UNPING procedure or function in dbms_shared_pool package.
4: There is no dbms_library_cache package in Oracle.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 855-857. Chapter 18: Tuning Memory and Operating System Use

---