Explanation
The construction of the Qutub Minar was initiated by Qutb-ud-din Aibak, the first Sultan of Delhi, in 1192. However, it was not completed during his lifetime.
The construction work was resumed by his successor, Iltutmish, who added three more stories to the minaret. The fourth and fifth stories were added by another Sultan, Firoz Shah Tughlaq, in the 14th century.
Therefore, the answer to your question is C: Iltutmish, who completed the construction of the Qutub Minar.