The Mongols under Gengis Khan invaded India during the reign of

Genghis Khan’s Central Asian campaigns reached the north-west frontier of the Indian subcontinent in the period 1219–1221, when Mongol forces pursued the Khwarazmian princes and crossed the Indus into the Punjab region [1]. This first major Mongol incursion toward India is dated to about 1221 and is described as a pursuit of Jalal ad‑Din into the Punjab, not a prolonged occupation. These events therefore occurred during the early decades of the Delhi Sultanate, when Shams al‑Din Iltutmish (r. early 13th century) was the principal ruler who confronted the Mongol threat and organised defence of the frontier. Hence the correct answer is Iltutmish.

Sources

1. [1] Themes in world history, History Class XI (NCERT 2025 ed.) > Chapter 3: Nomadic Empires > The Career of Genghis Khan > p. 65