Which Salesforce feature allows a developer to see when a user last logged in to Salesforce if real-time notification is not required?

A developer created a helper class with a method that can be called from Visualforce pages, web services, triggers, and of even anonymous code. When the method is called from a trigger, the developer needs to execute logic that should not be executed If the method Is called from anywhere else. How can the developer determine if the code Is executed in a trigger context?

A developer needs to test an Invoicing system integration. After reviewing the number of transactions required for the test, the developer estimates that the test data will total about 2 GB of data storage.
Production data is not required for the integration testing.
Which two environments meet the requirements for testing? (Choose two.)

What can used to delete components from production?

Which one do you like?
What should a developer consider for an environment that has over 10,000 Case records?