Which of the following North Indian languages was mainly used by the medieval poet Surdas in his devotional writings?

Introduction / Context:
Surdas is one of the most celebrated poet saints of the Bhakti movement in North India. He is especially known for his compositions devoted to Krishna and for his emotional lyrical style. Different regions of North India have their own dialects and languages, and it is important to know which linguistic tradition Surdas belonged to. This question asks you to identify the language used by him in his writings.

Given Data / Assumptions:
- The poet in question is Surdas, a medieval Bhakti poet.
- The options list several North Indian languages or dialects such as Awadhi, Khariboli, Braj, Bundeli, and Maithili.
- Only one of these was the primary language of Surdas compositions.

Concept / Approach:
Surdas is strongly associated with the Braj region and with Braj Bhasha, a Western Hindi dialect used in devotional poetry on Krishna. Many later poets also wrote in Braj for Krishna related themes. The strategy is to recall that connection and distinguish it from other dialects like Awadhi or Maithili which are linked to different poets and regions.

Step-by-Step Solution:
Step 1: Recall that Surdas composed the famous Sursagar and other devotional works centred on Krishna.
Step 2: Note that these works belong linguistically to Braj Bhasha, the dialect of the Braj region around Mathura and Vrindavan.
Step 3: Recognise that Awadhi is associated with poets like Tulsidas, while Maithili is linked with eastern regions and other poet traditions.
Step 4: Therefore, among the given options, Braj is the correct choice.

Verification / Alternative check:
As an alternative check, you can link poets with their typical dialects: Tulsidas with Awadhi, Vidyapati with Maithili, and Surdas with Braj. This pattern is often presented in literature and history textbooks. Remembering this table ensures the answer is reliable.

Why Other Options Are Wrong:
Option a is wrong because Awadhi is not the main language of Surdas, though it is an important literary dialect used by other saints.
Option b is wrong since Khariboli later developed into standard Hindi and Urdu prose but is not the dialect most closely connected with Surdas devotional songs.
Option d is wrong because Bundeli is a dialect of the Bundelkhand region, not the Braj area where Surdas devotional tradition is situated.
Option e is wrong as Maithili belongs mainly to eastern India and is not linked to Surdas.

Common Pitfalls:
Some learners confuse Awadhi and Braj because both are Western or Central Indo Aryan dialects and both appear in Bhakti literature. Another frequent error is to ignore regional associations and simply pick any familiar language name. Creating a small mental map that matches poets to dialects helps to avoid such mistakes.

Final Answer:
The language mainly used by Surdas in his writings was Braj.