A 45-year-old woman presents with heavy menstrual bleeding and iron deficiency anemia. On pelvic examination, the uterus is enlarged, and multiple irregularly shaped masses are palpated. Which condition is most likely to be responsible for these findings?

Correct Answer: A

Rationale: The clinical presentation of heavy menstrual bleeding, iron deficiency anemia, an enlarged uterus, and irregularly shaped masses palpated on pelvic examination is most indicative of leiomyomas, also known as uterine fibroids. Leiomyomas are benign smooth muscle tumors that commonly occur in women of reproductive age. They can lead to heavy menstrual bleeding and iron deficiency anemia due to their size and location within the uterus. On pelvic examination, leiomyomas can be felt as irregularly shaped masses within the uterine wall. This presentation is classic for leiomyomas and distinguishes them from conditions such as endometrial polyps, endometrial hyperplasia, and adenomyosis.

Correct Answer: C

Rationale: Among the given options, teratoma (dermoid cyst) is the most common type of ovarian tumor in women of reproductive age. Dermoid cysts are a type of ovarian teratoma that contains tissues derived from the ectoderm (skin), mesoderm (bone, muscle), and endoderm (mucous membranes). They are usually benign and can contain a variety of elements such as hair, teeth, bone, and sebaceous material. Serous cystadenomas and mucinous cystadenomas are more commonly seen in older women, whereas endometriomas are typically associated with endometriosis rather than being the most common ovarian tumor type in women of reproductive age.

Correct Answer: A

Rationale: IgA is the primary immunoglobulin class involved in providing passive immunity to newborn infants through breast milk. IgA antibodies are highly concentrated in colostrum and breast milk, offering important protection to newborns against infections. IgG antibodies can also be passed from the mother to the fetus through the placenta, providing passive immunity during pregnancy, but IgA is the main immunoglobulin class transferred through breast milk for protecting the infant's gastrointestinal and respiratory tracts. IgE is mainly involved in allergies and hypersensitivity reactions, while IgM is an early responder in the immune response to infections.

Correct Answer: B

Rationale: Major histocompatibility complex (MHC) class I molecules are responsible for presenting endogenous antigens, such as viral or intracellular proteins, to CD8+ T cells. These antigens are derived from within the cell, either synthesized within the cell itself or taken up from the cytoplasm. CD8+ T cells, also known as cytotoxic T cells, recognize antigens presented by MHC class I molecules and play a key role in cell-mediated immunity by destroying infected or abnormal cells.

Correct Answer: A

Rationale: The clinical findings of inspiratory crackles (also known as rales) and dullness to percussion are most consistent with a diagnosis of pneumonia. Inspiratory crackles are abnormal lung sounds heard on auscultation and are typically due to the presence of fluid or mucus in the alveoli. Dullness to percussion can indicate consolidation of lung tissue, which is a common finding in pneumonia where the alveolar spaces are filled with inflammatory exudate. These findings suggest localized lung pathology and are commonly observed in patients with pneumonia. Hemoptysis and pleuritic chest pain (Choice B) are more suggestive of pulmonary embolism or pleurisy. Clubbing of the fingers and cyanosis (Choice C) are signs of chronic hypoxemia and are not specific to pneumonia. Decreased breath sounds and tracheal deviation (Choice D) are more indicative of conditions such as a pneumoth