Answer:
Correct answer is bring back spices to Europe and sell them for a profit.
Step-by-step explanation:
The last option is the correct one as during the period of developed trade between Europe and Asia a famous Silk Road was established, through which Europeans were able to import certain products and goods, especially spices, that were not to be found in Europe.
First option is not correct as the number of sailors was not an important factor related to their explorations.
Second option is not correct as precious furs were not a product they traded for in this area.
Third option also is not correct as precious metals were not to be obtained in Asia. That developed when the New World was discovered.