In this task, you will be presented with a question and you have to answer the question based on your knowledge. Your answers should be as short as possible.
One example: Who were the builders of the mosque in Herat with fire temples ?
Solution is here: Ghurids
Explanation: This is a good example. Ghurids were the builders of the mosque in Herat with fire temples.

Now, solve this: How many stations have a frequency sub 1,000 ?
Solution:
5