Explanation:

- Surat was indeed the emporium of western trade during the Mughal period. It was a bustling port city in Gujarat and a major hub for trade with European and Asian merchants.

- Correct Answer: Option 4 - Surat

- Navsari was not primarily known as a major trade center during the Mughal era. It is famously associated with the Parsi community.

- Narmada refers to the river, not a trading port during the Mughal period.

- Porbandar is historically significant for different reasons but wasn't a central trade hub during the Mughal era.