Final answer:
The purpose of the voyage is to find gold or spices.
Step-by-step explanation:
The subject of this question is History. The question is asking about the main purpose or goal of a person's voyage at sea. From the provided information, it can be inferred that the purpose of the voyage is to find gold or spices in great quantity. This is evident from the quote by Christopher Columbus, where he mentions that he will remain at sea till he collects as much gold or spices as possible.
The correct answer to the question is a) Purpose, as the primary goal of the voyage is to find gold or spices.