The correct answer is: A. Uday Singh.
Uday Singh was the founder of the Kaithal principality in 1763 AD. He was a descendant of the Tomar Rajputs, who had ruled over the area for centuries. Uday Singh was a brave and capable ruler, and he quickly established the Kaithal principality as a powerful force in the region. He was succeeded by his son, Gurbaksh Singh, who continued to rule the principality with great success. The Kaithal principality remained a powerful force until it was annexed by the British in the early 19th century.
Option B, Gurbaksh Singh, is incorrect because he was the son of Uday Singh, who founded the Kaithal principality.
Option C, Gurudatt Singh, is incorrect because he was the grandson of Uday Singh.
Option D, Sardar Singh, is incorrect because he was the great-grandson of Uday Singh.