Indians had knowledge of monsoon winds since ancient times, and these winds across the Bay of Bengal played a crucial role in facilitating sea voyages. The monsoon winds not only enabled the movement of large ships but also smaller boats, allowing people and traders to travel to neighboring countries even without promotion by rulers[1]. This natural phenomenon provided a consistent and reliable means of maritime transportation.

The seasonally reversing winds in the Bay of Bengal are almost consistent during the monsoon period, creating predictable patterns that ancient mariners could utilize for navigation[3]. During the southwest monsoon (May through September), southwesterly winds prevail across the Bay of Bengal, while the northeast monsoon winds dominate during January[3]. These predictable wind patterns allowed sailors to time their voyages according to the seasons, making maritime trade possible and sustainable.

While India did have advanced shipbuilding technology dating back to the Harappan Civilization (around 2600-1900 BCE)[2][4], and southern Indian rulers did patronize traders and religious figures[1], the monsoon wind patterns provided the fundamental natural mechanism that made regular maritime trade possible. Without these favorable wind conditions, even the best ships and strongest political support would not have been sufficient to maintain consistent trade routes.

The maritime history of India shows that these trade routes were not controlled by a single power[4], suggesting that the natural advantage of monsoon winds was more important than political patronage in establishing and maintaining these connections. The monsoon winds created a natural highway across the Bay of Bengal that facilitated cultural exchange and trade relationships that lasted for centuries.

Therefore, option (c) represents the most convincing explanation for India's maritime preeminence in the Bay of Bengal region.