Approximately how much of earth’s land surface is made up of climate type b?

The correct answer is - around 1/4.

The climate types B are the tropical and subtropical arid and semiarid climates. They can be found between 50° north and 50° south, but in general, most of them are located between 15° and 30° latitude on both of the hemispheres.

In this climates, the most characteristic elements are the lack of precipitation, and the high temperatures, thus they are not very rich in plant and animal life.

The deserts and the steppes are the dominant biomes, and they are increasing their areas little by little each year, in a process that is known as desertification, which can well be attributed to the global changes in the climate.