Answer:
D. To illustrate his successes and advantageous discoveries to secure financial support for future voyages
Step-by-step explanation:
Christopher Columbus was sponsored by the Spanish government to conduct an expedition toward the Atlantic ocean. The purpose of this expedition is to find trade routes that Christian Merchants can use to conduct their trades.
He came across a route to American continent in 1492. He wrote his letter for the Spanish government to tell a story about his successful discoveries.
In the letter, he mentioned that he stumbled upon a land with great resources and wealth. He wanted the Spanish government to seize this and reward him for his effort to support his future voyages.