The number of a topographic map is 47A/16/NW. Its scale must be

1 : 250,000
1 : 100,000
1 : 50,000
1 : 25,000

The correct answer is: C. 1 : 50,000

The first two digits of the map number (47) refer to the state or province in which the map is located. The third digit (A) refers to the sheet number within the state or province. The fourth and fifth digits (16) refer to the quadrangle number within the sheet. The last two digits (NW) refer to the direction of the map’s orientation (north-west).

The scale of a topographic map is the ratio of the distance on the map to the actual distance on the ground. A scale of 1 : 50,000 means that every 1 unit on the map corresponds to an actual distance of 50,000 units on the ground.

The scale of a topographic map is important because it allows you to determine the actual distance between two points on the map. It also allows you to determine the size of features on the map. For example, if a feature is 1 cm wide on the map, it is actually 50,000 cm wide on the ground.

The scale of a topographic map is also important for determining the amount of detail that is shown on the map. A map with a large scale will show more detail than a map with a small scale. This is because a map with a large scale has a smaller area represented on each map unit.

In conclusion, the correct answer is: C. 1 : 50,000. The scale of a topographic map is the ratio of the distance on the map to the actual distance on the ground. A scale of 1 : 50,000 means that every 1 unit on the map corresponds to an actual distance of 50,000 units on the ground. The scale of a topographic map is important because it allows you to determine the actual distance between two points on the map. It also allows you to determine the size of features on the map.