Mariam has just recently gotten pregnant. Before she even found out, her embryo had already formed three germ layers. What is the layer that will develop into the nervous system?

Ectoderm

Explanation:

In addition to other structures, ectoderm gives rise to all the nervous tissues. Induction by notochord makes the ectodermal cells to form the neural plate. The elevated ends of the neural plate form the neural folds by the end of the third week of pregnancy. The fusion of neural folds gives rise to the neural tube. Brain and spinal cord develop from the neural tube. Some of the ectodermal cells transform into neural crest cells which in turn give rise to sensory neurons and the postganglionic neurons of the peripheral nerves.