A). Correct as then a PDB will get assigned the default directive with parallel_server_limit set to 0
B). Correct as parallel_server_limit is not specified for PDB3 and it defaults to 100 Quote:
https://docs.oracle.com/database/121/ADMIN/dbrm.htm#ADMIN14008
"If PARALLEL_SERVER_LIMIT is not specified, then it defaults to 100%."
C). Incorrect. A PDB can use more resources:
Quote from
https://docs.oracle.com/database/121/ADMIN/cdb_dbrm.htm#ADMIN13777
"However, any PDB can use more than the guaranteed amount of a resource if there is no resource contention."
D). Incorrect. Shares is a minimum guaranteed value. But a PDB can use more as explained above in C.
E). Incorrect. Nothing confirms that there are only 3 PDBs attached. There may be others using the default pdb directive. Then the share for PDB2 is not 20%
F). Incorrect. parallel_server_limit is an upper limit.