The Mughals were descendants of two great lineages of rulers. From their mother's side, they were descendants of Genghis Khan, ruler of the Mongol tribes. From their father's side, they were the successors of Timur, the ruler of Iran, Iraq and modern-day Turkey.
However, the Mughals did not like to be called Mongol because Mongol's especially Genghis Khan's memory was associated with the massacre of innumerable people. It was also linked with the Uzbeks, their Mongol competitors. On the other hand, the Mughals were proud of their Timurid ancestry, because it had achieved a good name in history.

Introduction:
The Mughals were a prominent dynasty that ruled over a vast empire in the Indian subcontinent from the 16th to the 19th centuries. They were known for their rich cultural heritage, architectural marvels, and administrative prowess. The Mughals traced their ancestry through their mothers' side to Genghis Khan, the founder of the Mongol Empire.

Explanation:
The correct answer to the question is option 'B' - Genghis Khan. Here's a detailed explanation of why the Mughals were descendants of Genghis Khan through their mothers' side:

Genghis Khan and the Mongol Empire:
Genghis Khan, born as Temujin in the early 13th century, was the founder and the first Great Khan of the Mongol Empire. He united the nomadic tribes of Mongolia and went on to establish the largest contiguous empire in history. The Mongol Empire stretched from Eastern Europe to the Sea of Japan, encompassing a significant portion of Central Asia.

Mughals and their Timurid lineage:
During the 14th century, Timur, also known as Tamerlane, emerged as a formidable conqueror in Central Asia. He was a descendant of Genghis Khan through his mother's side and claimed the legacy of the Mongol Empire. Timur's empire, known as the Timurid Empire, extended from modern-day Iran to India and Central Asia.

Babar and the Mughal Empire:
Babar, the founder of the Mughal Empire in India, was a direct descendant of Timur through his father's side. He inherited the Timurid legacy and established his rule in the Indian subcontinent after defeating the Delhi Sultanate in the Battle of Panipat in 1526. However, it is important to note that Babar also had ancestral connections to Genghis Khan through his mother's side.

Mughals and their Mongol lineage:
The Mughals, including Babar and his successors, considered themselves to be descendants of both Timur and Genghis Khan. This dual lineage gave them a sense of legitimacy and connected them to the illustrious Mongol heritage. The Mughal emperors took pride in their Mongol ancestry and often referred to themselves as "Gurkani," which means "son-in-law" of the Mongols.

Conclusion:
In conclusion, the Mughals were descendants of Genghis Khan through their mothers' side. While their direct ancestral connection to Genghis Khan was through Timur, the founder of the Timurid Empire, it is important to acknowledge that Babar and his successors also had ancestral ties to Genghis Khan through their mothers. This Mongol lineage played a significant role in shaping the Mughal identity and their claim to power in the Indian subcontinent.