Final answer:
a. 1746.
The 'Chhota Ghalughaara' or First Holocaust occurred in the year 1746, marking a significant event in Sikh history where a great number of Sikhs were massacred by Mughal authorities.
Step-by-step explanation:
The 'Chhota Ghalughaara' or the First Holocaust, which is distinct from the Holocaust that occurred during World War II, refers to a lesser-known but significant event in Sikh history. The 'Chhota Ghalughaara' took place in the year 1746. During this tragic event, a large number of Sikhs were killed by the Mughal authorities in what is now the Punjab region of India. This event is marked as a traumatic period in Sikh history, similar to the Holocaust experienced by the Jewish people during the Nazi regime, albeit on a different scale and context.