Which of the following is the datum used for the majority of charts worldwide?

The datum used for the majority of charts worldwide is WGS 84. This global positioning standard is used as a reference framework for geographic data and is essential for ensuring consistency in navigation and positioning. WGS 84 allows for accurate measurements and mapping across various terrains and platforms, making it indispensable for integration with GPS technology. Its widespread adoption facilitates global navigation and supports international cooperation in maritime activities, which is crucial for vessels traversing international waters and operating in diverse navigational environments.

In contrast, the other options serve more localized or specific purposes; for instance, NAD 83 is primarily used in North America, while ED50 is more associated with European cartography and older systems. DEF 90 is not as commonly referenced in the context of global navigation and charting as WGS 84. Thus, WGS 84's comprehensive application and recognition as an international standard make it the correct choice for this question.