Step 1: AIDS-related complex (ARC) is a symptomatic but pre-AIDS stage of HIV (CDC class B). It features constitutional symptoms and opportunistic conditions caused by progressive immune weakening.
Step 2: Recall the typical ARC features - persistent generalised lymphadenopathy, long-lasting diarrhea (over four weeks), unexplained weight loss, prolonged fever, night sweats, recurrent candidiasis (oral or genital), herpes zoster, oral hairy leukoplakia, and cervical dysplasia in women.
Step 3: Check the options. Recurrent genital candidiasis (b), generalised lymphadenopathy (c), and chronic diarrhea (d) are all classic ARC manifestations.
Step 4: Ectopic pregnancy (a) is an obstetric/gynaecological emergency from implantation outside the uterus. It has no causal link to HIV immune suppression and is not part of ARC. Hence the answer is (a).