Given a scientific question, generate a correct answer to it.

Example Input: What is continually released during childbirth through a positive feedback mechanism and prompts uterine contractions to fetal head toward the cervix?
Example Output: oxytocin

Example Input: What current-carrying long coil of wire acts as a magnet?
Example Output: solenoid

Example Input: The dead, dry stratum corneum is the most superficial layer of what and is the layer exposed to the outside environment?
Example Output:
epidermis