A .False. "Logging out to the abc database" is nonsensical; abc is a script, not a database.
B .False. SQL*Plus finds abc.sql in the current directory by default; a full path isn't required unless it's elsewhere.
C .False. The first @ specifies the TNS alias (orcl), the second runs the script (@abc); this is valid syntax.
D & E.True (identical options). The command connects to orcl via TNSNAMES.ORA, authenticates HR, and executes abc.sql.
Mechanics:sqlplus hr/hr@orcl resolves orcl to a listener address, connects, and@abc runs the script post-login.