What documents must a pilot have readily accessible in the aircraft while acting as pilot in command?

The requirement for a pilot to have certain documents readily accessible while acting as pilot in command primarily revolves around ensuring that they possess the necessary qualifications to operate the aircraft safely and in compliance with aviation regulations. The correct answer highlights that a pilot must have an appropriate pilot certificate, which serves as proof of the pilot's qualifications, and a current medical certificate, which demonstrates that the pilot meets the necessary health standards to safely fly an aircraft, if required.

The pilot certificate is essential as it indicates that the pilot has completed the various training and testing required to operate a specific category and class of aircraft. The medical certificate is also crucial because it ensures that the pilot does not have any medical conditions that could impair their ability to fly. Regulations mandate that these documents be available in the aircraft during flight to ensure compliance and safety.

The other options mentioned may include elements that are relevant to a pilot's qualifications, such as endorsements or specifics regarding flight reviews. However, they do not cover the fundamental requirement of having a proper pilot certificate and medical certificate, which are the essential documents mandated under aviation regulations for pilots in command.