Answer:
The correct answer is The citizens of Athens stayed within an overcrowded walled city.
Step-by-step explanation:
Pericles decided to move all the citizens to the city, believing the city walls will protect. Still, there were too many people in the city, the plague broke out and the population was devastated. Even Pericles died.
All other options are not a main reason why the Pericles strategy failed, although Persia did support Sparta in this conflict, and at the end Sparta managed to defeat Athens.