If 16 flight lines are run perpendicular to an area 30 km wide, their spacings on a photographical map on scale 1 : 50,000 , will be

Answer: Option D

Let's break down this surveying problem step by step!

First, we need to understand what the question is asking.
It's about the spacing between flight lines on a map, given a real-world area and a map scale.

The area's width is 30 km, and there are 16 flight lines perpendicular to it. This means the 16 flight lines divide the 30 km width into 15 equal spaces.
Therefore, the spacing between the flight lines on the *ground* is calculated as: 30 km / 15 = 2 km.

Next, we need to convert this ground distance to the map distance using the scale 1:50,000.
This scale means that 1 unit on the map represents 50,000 units on the ground.

Convert the ground distance (2 km) to centimeters: 2 km = 2 * 1000 m = 2 * 1000 * 100 cm = 200,000 cm.

Now, apply the scale to find the map distance: Map distance = Ground distance / Scale factor = 200,000 cm / 50,000 = 4 cm.

Therefore, the spacing between the flight lines on the photographical map will be 4 cm.

So, the correct answer is: Option D: 4 cm.