Outline the steps to disassemble and reassemble the M4 upper and lower receivers.

• A. Ensure weapon is clear; remove magazine; push/take down pins to separate upper from lower; remove or inspect bolt carrier group and charging handle as needed; reassemble in reverse and verify pins are secure.
• B. Shoot it until it splits.
• C. Turn the weapon upside down and shake it apart.
• D. Disassemble by removing the optic and stock.

Answer: (A)