The correct option is C Battle of Nadaun
In the battle against the Mughals, Guru Gobind Singh tried to help the kings of the hill states in the Battle of Nadaun in 1690. Ironically, the kings of hill states went to war with Guruji. It made him realise that the Sikhs would have to fight for themselves to uphold and preserve the values of Sikhism. Thus, he established the brotherhood of the Sikhs, also known as Khalsa.