Consider the following statements
1. Guru Gobind Singh Ji founded the Institution of 'Khalsa'.
2. He built the fort Anandgarh at Anandpur.
3. He affirmed the Adi Granth as the perpetual Guru of the Sikhs.
4. He wrote the 'Zafarnama', a letter to meet Aurangzeb.
Which of the statement(s) given above are correct in relation to Guru Gobind Singh?

A. 1, 2 and 3

B. 2, 3 and 4

C. 3 and 4

D. All of the above

Answer: Option D