Final answer:
The most important detail for the Spanish King and Queen would be the consolidation of royal rule and the increase in commerce and industry during their reign.
Step-by-step explanation:
The most important detail for the Spanish King and Queen would be the consolidation of royal rule and the increase in commerce and industry during their reign. This is because it signifies the growth and development of Spain as a nation during their rule. By lessening the power of the nobles and attracting trade from the Mediterranean world, Ferdinand and Isabella were able to strengthen the monarchy and expand Spain's influence.