Muhammad-bin-Tughlaq was proficient in

Muhammad-bin-Tughlaq, the Sultan of Delhi from 1325 to 1351, was known for his intellectual brilliance and scholarly pursuits.

He had a deep interest in philosophy, logic, mathematics, astronomy, and physical sciences, which made him stand apart from other rulers of his time.

Though he was well-educated and had knowledge of art, literature, and religion, his greatest proficiency was in philosophy. He often engaged in discussions with scholars and thinkers.

Therefore, the correct answer is Philosophy