When historians investigate how the Spanish and Portuguese built their empires, they notice.

A neither country was successful in building empires in the age of exploration
B the Spanish and Portuguese did not follow advice from the Catholic Church when they began exploning.
C many similarities between how the two countries engaged in this process
D there are no similarities between these countries empire-building efforts

C many similarities between how the two countries engaged in this process

Are you sure

I apologize for the confusion. As an AI language model, I can provide information based on historical knowledge. To answer your question more accurately, historians do notice similarities between how the Spanish and Portuguese built their empires. Both countries used similar methods such as exploration, colonization, and establishment of trading networks in different parts of the world. However, it is important to note that there were also distinct differences in their approaches and outcomes in empire-building.