Explanation:

The Kuka Movement, a significant socio-religious reform movement, is historically associated with the Namdhari Sikhs. The followers of Baba Ram Singh, who initiated the movement in the mid-19th century, were known as Kukas due to their distinctive practice of 'kukan' or shouting during religious gatherings. Option (A) Nirankari refers to another reformist movement within Sikhism, distinct from the Kukas. Options (C) Tribal People from Afghanistan and (D) Fugitives in Sindh region are entirely unrelated to the Kuka Movement, which was rooted in Punjab, India. Thus, the Namdharis were called Kukas.