According to Trailhead2, Salesforce Connect is a feature that allows administrators to integrate external data sources with Salesforce without copying or synchronizing the data. Salesforce Connect can use external objects to display the external data in Salesforce as if it were stored in Salesforce objects, enabling seamless user experience and real-time access. Option B is the correct answer because it suggests using Salesforce Connect and an external object to display the order history in Salesforce. Option A is incorrect because using an Apex callout to populate a text area field for displaying the order history can be inefficient and unreliable, as it requires making an HTTP request for each customer record and storing the order history as unstructured text. Option C is incorrect because importing the order history into a custom Salesforce object, update nightly can consume a lot of storage space and cause data latency, as the order history may change more frequently than once a night. Option D is incorrect because embedding the ERP system in an iframe and displaying on a custom tab can degrade the user experience and security, as it requires switching between tabs and authenticating with another system.