What does a blue sign with a white "H" mean?

Answer: A — Hospital ahead.

A blue sign with a white "H" means that there is a hospital ahead. This sign is used to warn drivers that a hospital is up ahead and to be alert for ambulances, pedestrians, and other traffic entering or exiting the hospital. The other options of a highway exit, hotel or motel, and historic site are incorrect because they do not have a specific designated sign and are typically indicated with other types of signs. Additionally, the white "H" is the international symbol for hospitals, making A the most accurate answer.