Question

Why did Italian merchants join the efforts of Portuguese mariners in searching for an Atlantic route to India in the fifteenth century?

c. Waning French power in the Mediterranean opened the way for them.
d. Italians were eager to obtain an alternative source of slaves outside the Middle East.
b. The weakening of the Ottoman Empire made it possible for them to ship through the Strait of Gibraltar and into the Atlantic.
a. The rising power of the Ottoman Empire restricted their overland access to Asian trade.

Answer 1

"a. The rising power of the Ottoman Empire restricted their overland access to Asian trade" is the best option since many trade routes were taken away.