Teratomas are benign tumors composed of tissues derived from all three primary germ layers: ectoderm, mesoderm, and endoderm. They are most common in the ovary but also occur in the testis and extragonadal sites. Adenoma (choice A) is a benign tumor of epithelial origin. Chondroma (choice B) is a benign cailaginous tumor. Hamaoma (choice C) is disorganized normal tissue.