The correct answer is option 3: Muhammad bin Tughlaq. He was one of the Sultans of Delhi who introduced the concept of token currency in his reign. Let`s discuss the other options to better understand why they are not the correct answers.

Option 1: Balban was a powerful ruler of the Delhi Sultanate, but he did not introduce token currency. He focused more on strengthening the central authority and maintaining law and order.

Option 2: Alauddin Khalji was another important ruler of the Delhi Sultanate. While he made significant reforms in the economic system, he did not introduce token currency.

Option 4: Firoz Tughlaq was known for his administrative capabilities and his policies to uplift the common people. However, he did not introduce token currency either.

Therefore, the correct answer remains option 3. Muhammad bin Tughlaq introduced token currency during his rule to alleviate the economic issues of the time. It was a form of currency made of base metals and had significantly less value than the precious metals used in regular currency. However, the introduction of token currency caused more economic problems and led to inflation, eventually leading to its abandonment.