Which of the following statements is false?

a. Lists and tuples are built-in sequence collections.
b. Dictionaries, strings and sets are built-in non-sequence collections.
c. A dictionary is an unordered collection which stores key–value pairs that map immutable keys to values, just as a conventional dictionary maps words to definitions.
d. A set is an unordered collection of unique immutable elements.

b. Dictionaries, strings and sets are built-in non-sequence collections.