The most responsible for making possible the voyages shown on the map is:
A) Henry the Navigator
Henry the Navigator was instrumental in promoting the exploration of the African coast and the Atlantic Ocean, although it's worth noting that he wasn't a king or ruler. He played a significant role in gathering knowledge and resources that supported later explorers. However, if the map specifically refers to voyages during the Age of Exploration attributed to Spain, then D) Queen Isabella and B) King Ferdinand could also be considered significant due to their sponsorship of Christopher Columbus' voyages.
If the question pertains generally to early exploration, then A) Henry the Navigator is the best choice. If it's more specific to Spanish exploration, then D) Queen Isabella or B) King Ferdinand may be more relevant. Please provide more context if available.