Question: What is key difference between a `set` and a `list`?

1. A set is an ordered collection unique items. A list is an unordered collection of non-unique items.
2. Elements can be retrieved from a list but they cannot be retrieved from a set.
3. A set is an ordered collection of non-unique items. A list is an unordered collection of unique items.
4. A set is an unordered collection unique items. A list is an ordered collection of non-unique items.

Answer: The correct answer of the above question is Option D:A set is an unordered collection unique items. A list is an ordered collection of non-unique items.