You Arrive at a Residence for a Call for an Unknown

You arrive at a residence for a call for an unknown problem. Outwardly, the scene appears safe. When you knock on the door, a distraught school-age child opens the door and says his father is holding his teenage sister and his mother hostage in a bedroom. Which of the following is the best course of action?

A) See if the child can get his father to agree to allow you to assess the hostages so you can inform law enforcement whether or not they have been harmed.
B) Retreat with the child, request law enforcement, and stage around the corner from the residence until law enforcement notifies you that the scene is secure.
C) Shout up the stairs that you are there to help in any way you can and see if you can talk the father down.
D) Find out from the child what kind of weapon is being used so you can decide if it is reasonable to overpower and restrain the father until law enforcement arrives.