Step 1: The question tests the approved indication for menopausal hormone therapy. Menopause is driven by falling estrogen, which causes vasomotor and urogenital symptoms.
Step 2: HT replaces estrogen and directly relieves vasomotor symptoms. Hot flashes, night sweats, sleep disturbance and vaginal dryness are the classic estrogen-deficiency symptoms it treats. HT is also approved for prevention of osteoporosis.
Step 3: Therefore hot flash (option a) is the correct indication.
Step 4: The distractors are actually contraindications or unrelated: estrogen-dependent carcinoma of the breast (option b) is a contraindication to HT, endometriosis (option c) is estrogen-driven and can be aggravated, and undiagnosed uterine bleeding (option d) must be investigated, not treated with HT.