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

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

Output: oxytocin

Input: Consider Input: Amino acids are joined together to form a chain at what molecular structure?

Output: ribosomes

Input: Consider Input: What type of waves carry energy through matter or space as vibrating electric and magnetic fields?
Output: electromagnetic waves