سوال ۲۵ کنکور ارشد علوم کامپیوتر ۱۴۰۴

Read the relevant excerpt from Passage 3 and answer the question.

Passage 3 (excerpt): "In programming, we very frequently we have to represent complex structures. Imagine writing a program which has an internal representation of the map of the London Underground, plus some game configurations or rules of English grammar. [1] Describing these objects adequately requires the use of complex data structures. [2] Fortunately, objects such as the ones mentioned have been very well studied by mathematicians. [3] The mathematical way of describing such systems can then be readily translated into a data structure to be used in our programs. [4]"

In which position marked by [1], [2], [3] and [4], can the following sentence best be inserted in the passage?

Or rather, no mathematician studied the London Underground map, but many have studied graph theory, using which it is straightforward to describe the map of the London Underground.