ovulation
Explanation: ovulation is the release of eggs(ova) from the ovaries is the cycle of change which occurs in female reproductive system for a month.
One reason is if someone is injured and needed to use pain pills, sometimes they get addicted to it
White blood cells are made in the bone marrow. They are stored in your blood and lymph tissues. They help the body fight infection and other diseases.
Answer: The exoplanets are the planets which orbit stars other than the sun.
Explanation: Exoplanets are also known as extra solar planets which means that these planets revolve or orbit around the stars other than the sun.
Exoplanets does not belong to our solar system because in our solar system, the planets orbit around the star named as sun.
Examples of exoplanets are Kepler-186f , 55 Cancri e.