The correct answer is option 4, Philosophy.

Muhammad-Bin-Tughlaq, who was the ruler of the Delhi Sultanate in the 14th century, was known for his intellectual pursuits and interest in various fields of knowledge. However, out of the options given, Philosophy is the most accurate choice.

Philosophy is a branch of knowledge that deals with fundamental questions about existence, knowledge, values, and reasoning. It involves critically analyzing and examining concepts, beliefs, and theories. While Muhammad-Bin-Tughlaq was known for his intelligence and scholarship, there is no specific evidence to suggest that he excelled in art, music, or calligraphy. Instead, he was renowned for his philosophical inclination and his reforms in governance, which reflected his philosophical thinking. However, it is important to note that historical records are not always complete, so there could be other areas of proficiency that were not mentioned or are not well-documented.