A Store Manager for Kroger Noticed That Several of His

A store manager for Kroger noticed that several of his regular customers have stopped coming to his store. He also noticed that most of these customers had started shopping at the Walmart Supercenter that had opened about a mile from Kroger a few months ago. The fundamental source of this marketing problem might best be described as

A) a planned change in the marketing environment.
B) serendipity.
C) an unplanned change in the marketing environment.
D) a planned change that occurred at the Kroger store.
E) None of the above.