The cause of this change in the sales of the grocery shop is migration.
The factory was the main source of income for the people that stayed there. So given that the factory is no more, people left to seek for better job opportunities elsewhere.
And given that the people who have left where the ones patronizing the grocery shop, the sales of the shop would end up falling because the customers are no longer around.
What is migration?
Migration can be defined as the movement of people from one geographical location to another. People migrate to experience better life else where.
Read more on migration here:
https://brainly.com/question/1213023
