Question

This city is the largest in the state. Pittsburgh Erie Philadelphia Scranton

Answer 1

Erie has 100 000 people, and Pittsburgh has 300 000 - so from the first two Pittsburgh is the bigger one. 

Philadelphia has 1.5 million people living in it - it is also the biggest city in Pennsylvania (this is the state where all the cities are) - and this is also the correct answer!

It is not the capital however, as it's Harrisburg.