Iltutmish:
Iltutmish was the third Sultan of Delhi and ruled from 1211 to 1236. He was known for his administrative reforms and military prowess. Despite being a powerful ruler, Iltutmish was known for his accessibility and willingness to engage with common people. He often held open court sessions, where people from all walks of life could approach him and present their grievances.

Balban:
Balban, also known as Ghiyasuddin Balban, was the ninth Sultan of Delhi and ruled from 1266 to 1287. Unlike his predecessor, Balban was known for his strict and authoritarian rule. He believed in the absolute authority of the Sultan and maintained a strict hierarchy in society. Balban refused to speak to common people directly and preferred to communicate through his nobles and courtiers. This approach was aimed at maintaining his image as a powerful and unapproachable ruler.

Ala-ud-din Khalji:
Ala-ud-din Khalji was the second ruler of the Khalji dynasty and ruled from 1296 to 1316. He was known for his military campaigns and administrative reforms. While he was a stern ruler, Ala-ud-din Khalji did not refuse to speak to common people. In fact, he encouraged a system called the "Door of Complaints" where anyone could approach him with their grievances. He also implemented various economic and social policies to benefit the common people.

Firoz Tughlaq:
Firoz Tughlaq was the third Sultan of the Tughlaq dynasty and ruled from 1351 to 1388. He is known for his architectural projects and his focus on welfare policies. Firoz Tughlaq was known for his accessibility and willingness to engage with common people. He often held public audience sessions where anyone could approach him directly and present their grievances. He also implemented various welfare measures such as free hospitals, free education, and pensions for the poor.

Therefore, the correct answer is option 'B' - Balban, as he was the Sultan who refused to speak to common people directly and preferred to communicate through intermediaries.