Inside layer.

Inside layer.

• A. Endocarditis
• B. Endometriosis
• C. Endoderm
• D. Endocytosis

Answer: (C)

The main idea is recognizing a term that means the inner layer in embryology, using word parts. The prefix endo- means inside, and -derm refers to a layer or skin. Put together, endoderm is the inner germ layer of the embryo, the layer that gives rise to the lining of the digestive and respiratory tracts and related organs. That direct sense of “inside layer” is why endoderm fits best. The other terms point to different concepts: endocarditis is inflammation of the inner lining of the heart, not a developmental layer; endometriosis involves tissue similar to the uterine lining growing outside the uterus; endocytosis is a cellular process of taking substances into a cell.

The main idea is recognizing a term that means the inner layer in embryology, using word parts. The prefix endo- means inside, and -derm refers to a layer or skin. Put together, endoderm is the inner germ layer of the embryo, the layer that gives rise to the lining of the digestive and respiratory tracts and related organs. That direct sense of “inside layer” is why endoderm fits best.

The other terms point to different concepts: endocarditis is inflammation of the inner lining of the heart, not a developmental layer; endometriosis involves tissue similar to the uterine lining growing outside the uterus; endocytosis is a cellular process of taking substances into a cell.