I'm not so happy about the concept of learning the right answer for an interview questions. Like many other fields, being a good ETL (or ELT for that matter) developer requires knowledge, experience etc.
That said, many of the transformations in DI Studio can be used both as ETL and ELT. It also depends on how you define ELT.
One example is Join, where you can mark it to use explicit SQL pass-through. But that doesn't necessary means ELT, unless you specify the output to be in the same database.
So I would say it's rather a DI Studio job design pattern, rather than using specific transformations. Which is good, you don't lock yourself with ELT/ETL paradigms, you can switch quite easily without replacing the transformations.
Data never sleeps