The correct answer is option 1, Mathura Museum. The Mathura Museum is known for housing the largest collection of Kushan sculptures. These sculptures were created during the period of the Kushan Empire, which existed from the 1st to the 3rd century CE. The Kushan sculptures are significant because they showcase the blending of Hellenistic and Indian artistic styles. The Mathura Museum, located in Mathura, Uttar Pradesh, India, holds a vast collection of these sculptures, showcasing the rich artistic heritage of the Kushan Empire. It is an important destination for art enthusiasts and historians interested in studying and appreciating these unique sculptures. It is worth noting that the other options mentioned (Bombay Museum, Madras Museum, and Delhi Museum) may house other valuable collections, but they do not have the largest collection of Kushan sculptures.