Who is the most populated city in Pakistan?
As of 2021, the most populous city in Pakistan is Karachi, with an estimated population of over 16 million people.
Complete the following task based on the instruction and optional input provided.### Instruction:
Who is the most populated city in Pakistan?

### Output:
As of 2021, the most populous city in Pakistan is Karachi, with an estimated population of over 16 million people.