What significant event did the line of demarcation established by Pope Alexander IV lead to?

The line of demarcation established by Pope Alexander IV in 1493 was a pivotal moment in the Age of Exploration, primarily regarding territorial claims made by Spain and Portugal. This line, drawn to resolve disputes over newly discovered lands, effectively divided the non-European world between these two nations. Spain received the rights to lands to the west of the line, while Portugal was granted rights to the east. This division was integral to the expansion and colonization efforts of both countries, allowing them to lay claim to vast territories in the Americas and beyond without conflict between them.

The other options are not as relevant in this context. Spanish colonization of Asia did occur later, but the line of demarcation specifically addressed the New World. The creation of the first missions is related to Spain's efforts to establish its presence in the Americas, which stemmed from this territorial division, but is not directly a result of the line itself. Mapping the Texas coastline was part of the overall exploration efforts but was not directly related to the line of demarcation. Thus, option B accurately captures the significant consequence of the line established by Pope Alexander IV.