What is an iterator in Python?

The correct answer is Option C: An object that produces values one at a time.
An iterator in Python is an object that produces values one at a time. It implements two methods, iter() and next(), which enable it to be iterated over using a for loop or by calling the next() function. When iterating over an iterator, it produces values lazily, generating the next value only when requested. This lazy evaluation mechanism allows iterators to efficiently handle large datasets or infinite sequences without loading all values into memory at once.