Pelvic Inflammatory Disease (PID) is an infection of the upper female genital tract.
It commonly includes endometritis (inflammation of the uterine lining), salpingitis (inflammation of the fallopian tubes), and pelvic peritonitis (infection of the pelvic peritoneum).
These are classic components of PID and are serious causes of infertility and chronic pelvic pain.
Cervicitis is inflammation of the cervix and is usually considered a lower genital tract infection — it may lead to PID if untreated but by itself is not included as PID.
Therefore, A, B, and C are correct.