What is required of Boat A when approaching Boat B head-on in darkness or reduced visibility?

When Boat A approaches Boat B head-on in darkness or reduced visibility, both vessels are required to take action to avoid a collision. According to the International Regulations for Preventing Collisions at Sea (COLREGs), both boats should alter their course to starboard, allowing them to pass each other on the port side. Additionally, both vessels must maintain a proper lookout, ensure safe speed, and use appropriate navigation lights to indicate their presence.