Which conditions are characterized by elevated hCG levels?

Elevated levels of human chorionic gonadotropin (hCG) are primarily associated with conditions involving the placenta or trophoblastic tissue. Choriocarcinoma is a malignant tumor of trophoblastic origin, often arising in the uterus from gestational tissue following a pregnancy, typically marked by significantly increased hCG levels. Hydatidiform mole, or molar pregnancy, is a result of abnormal fertilization leading to the development of a mass of cysts instead of a normal embryo. This condition also results in elevated hCG levels due to the presence of trophoblastic tissue.

Both conditions highlight the role of hCG in monitoring and diagnosing gestational trophoblastic diseases. In contrast, the other options listed do not involve the elevation of hCG levels—Ghon complex pertains to tuberculosis, megaloblastic anemia is related to vitamin deficiencies (like B12 and folate), and bronchial asthma along with EBV mononucleosis are not associated with hCG release. Thus, the association of elevated hCG levels is distinctly linked to choriocarcinoma and hydatidiform mole, making this choice the correct answer.