Which of the following tiles can be used to control the flow in a customer journey?

The splitter tile is used to control the flow in a customer journey by allowing marketers to segment their audience based on specific criteria or behaviors. When implemented, it can create two paths in the journey, enabling different messaging or actions for different segments of customers. This functionality is critical in marketing automation as it allows for tailored communications, enhancing engagement and improving the overall effectiveness of campaigns.

The internal action item, while providing a way to assign tasks within the journey, doesn't influence the flow or path taken through the journey itself. The trigger tile activates actions based on customer interactions but does not directly dictate the path options. The scheduler is designed to set timing for actions rather than controlling the journey's flow. Thus, the correct answer is the splitter, as it is specifically designed to segment and navigate the journey effectively based on customer actions or characteristics.