The correct option is C Mesoderm
The three germ layers (the ectoderm, the mesoderm and the endoderm) are in place at the end of gastrulation and gives rise to different parts of the organism. The mesoderm gives rise to connective tissue (cartilage and bone), striated and smooth muscles, the heart walls, blood, lymph vessels, kidneys, gonads, spleen and notochord.
Thus, the correct answer is option C.