Explanation
Einstein Content Selection is a feature that uses artificial intelligence to automatically select the best content for each subscriber based on their engagement history and preferences. It can help increase click rates by delivering personalized and relevant content in emails.

Explanation
Editing the fields in the synchronized data source is the first step to ensure the new fields are available to segment on. The marketer needs to select which fields they want to sync from Salesforce to Marketing Cloud, and then wait for the sync process to complete. Creating a new data extension or a data filter with the new fields would not work if the fields are not synced first.

Explanation
Content Builder > Recent Sends is the correct answer. This option allows you to view the delivery rate and other metrics of the most recent email sends from your business unit. You can also drill down into each send to see more details, such as the number of delivered, bounced, opened, or clicked emails. Automation Studio > Activities is not a valid option, as this option only shows the status and schedule of your automation activities, not the metrics of your email sends. Email Studio > Overview is not a valid option either, as this option only shows the summary and trend of your email performance across all business units, not the specific metrics of your recent email sends. You can learn more about this in the [Email Reporting Tools] module on Trailhead.

Explanation
User Initiated Send is the method that the specialist should use. User Initiated Send is a feature that allows you to create and send an email message to one or more data extensions or lists at any time. You can also schedule the send for a future date and time or set it to recur at regular intervals. You can use this feature to automate sending the weekly newsletter to subscribers in one data extension and a partner seed list. Multi-Step Journey is not necessary if you only want to send one email message without any other journey activities.
Automation Studio Email Activity is not suitable if you want to send to a partner seed list, as it only supports data extensions as sendable audiences.

Explanation
Einstein Content Selection is the feature that NTO should use to build a welcome journey for new customers with dynamic content in each email. Einstein Content Selection allows marketers to create personalized content for each customer based on their behavior and preferences, and also include assets that are automatically optimized based on real-time performance data. Einstein Content Selection can be used with Content Builder to create dynamic content blocks that can be inserted into emails and journeys.