A developer wants to configure performance tracking of the content dynamically created via AMPscript in an email. Which two steps should be performed to achieve this objective? Choose 2

A doctor's office creates Populations for staff, patients and vendors. What is the maximum number of Populations that should be created to ensure performance?

A developer is using the REST Authorization Service to obtain an OAuth access token. Which method should be used to include the access token in the API requests

A developer wants to personalize a welcome email with the recipient's first name from the Customers data extension, which is different from the targeted sending data extension named NewSubscribers. Both data extensions contain the unique identifier in a field named CustomerKey. Which AMPscript Syntax would populate the first name personalization as requested?

A developer identified a use case where a triggered send of an email is needed. The developer already successfully set up authentication with a Client ID and Client Secret has used them in several REST calls. When the REST call is made, a "401 Unauthorized" error is returned. What is the first thing the developer should check?