a) The main argument in the passage about Indian Ocean ports is that they were many and accommodated varied-sized ships from many parts of the world.
b) The ONE factor that enabled Calicut to become a regional trade hub is its geographical location as a coastal city. Its port accommodated various ships and the products sought after in other parts of the world, especially the spices.
c) The similarities between the commercial interactions of the regions and the Silk Roads were that the interactions, just like the Silk Roads, created trading cities and independent kingdoms. People from various locations in the world converged to these trading locations, bringing in their different cultures that enlivened and enriched the trading cities.
Thus, the passage developed the advantages that accrue to cities with natural trade facilities.
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