The correct answer is A. One cm measured on the map is equal to fifty thousand cm (or 500 meters) in reality. This is commonly referred to as the map scale ratio, where the first number represents the map distance and the second number represents the actual ground distance. So, a map with a scale of 1:50,000 means that one unit of measurement on the map (such as one centimeter) represents 50,000 units of measurement on the ground (such as 50,000 centimeters or 500 meters).