The entry port for trade between the Indus trading centres and Mesopotamia was None of these. The correct answer is option 'D' because there is no specific entry port mentioned in historical records for trade between the Indus trading centres and Mesopotamia.

Explanation:

1. Indus Valley Civilization:
The Indus Valley Civilization was one of the earliest urban civilizations in the world, flourishing from around 2500 BCE to 1900 BCE. The civilization was spread across modern-day Pakistan, India, and parts of Afghanistan.

2. Indus Trading Centres:
The Indus Valley Civilization was known for its advanced urban planning, trade, and commerce. The major trading centres of the Indus Valley Civilization included Harappa and Mohenjo-Daro, which were located along the banks of the Indus River.

3. Mesopotamia:
Mesopotamia, on the other hand, was an ancient region located in present-day Iraq and parts of Syria, Iran, and Turkey. It was one of the earliest civilizations in the world, known for its advanced agricultural techniques, trade, and commerce.

4. Trade between Indus and Mesopotamia:
There is evidence of trade and cultural exchange between the Indus Valley Civilization and Mesopotamia. Archaeological findings have revealed the presence of Indus Valley seals and pottery in Mesopotamian cities like Ur and Uruk.

5. Lack of specific entry port:
However, there is no specific entry port mentioned in historical records for trade between the Indus trading centres and Mesopotamia. The exact routes and modes of transportation used for trade are not well-documented.

6. Possible trade routes:
It is believed that trade between the two regions might have taken place through overland routes, such as through the Khyber Pass in modern-day Pakistan, or through coastal routes along the Arabian Sea.

7. Coastal trade:
Coastal trade along the Arabian Sea might have involved the use of small boats or ships to transport goods between the trading centres. However, the exact details of these trade routes are still subject to speculation and ongoing research.

In conclusion, while trade and cultural exchange between the Indus Valley Civilization and Mesopotamia did exist, there is no specific entry port mentioned in historical records. The routes and modes of transportation used for trade between the two regions are still not well-documented.