5. (10 pts) Please read the code segment and answer the five sub-questions.
申論題內容
(e)(2 pts) When sigaction() on line 17, 19, and 21 are replaced by signal(), what's the signal mask after resumed by
catching SIGINT? (A) SIGUSR1 and SIGUSR2, (B) SIGUSR1, (C) SIGINT and SIGUSR2, and (D) Empty.