In a single record, a user selects multiple values from a multi-select picklist. How are the selected values represented in Apex?

A developer is asked to set a picklist field to 'Monitor' on any new Leads owned by a subnet of Users.
How should the developer implement this request?

What is the advantage of Salesforce Lightning?

As part of a data cleanup strategy, AW Computing wants to proactively delete associated opportunity records when the related Account is deleted.
Which automation tool should be used to meet this business requirement?

A businessimplemented a magnification plan to encourage its customers to watch some educational videos.
Customers can watch videos over several days, and their progress is recorded. Award points are granted to customers for all completed videos. When the video is marked as completed in Salesforce, an external web service must be called so that points can be awarded to the user.
A developer implemented these requirements in the after update trigger by making a calf to an external web service. However, a System.CalloutException is occurring.
What should the developer do to fix this error?