A software company wants to get an idea of their customers' level of satisfaction with their software. To do so, they included a phone number on the packaging of their most recent software release, with the message, "If you have any concerns with the product, please call this number." Based on the overwhelmingly negative response they received from these calls, the company decided to stop selling the product.

What could be wrong with their decision?

A.
The phone system screened out certain positive comments because of a malfunction.
B.
The release of the software coincided with the spread of a virus which affected the performance of the program.
C.
The note on the package only told customers to call in the event that they had a concern, which could bias the results negatively.
D.
The customers were misinformed about the purpose of the program.

Since customers were only told to call if they had concerns, all of the calls were about concerns or problems that they were having - meaning all of the calls were negative. However, they were never informed to call if they were happy or content with the product, meaning they were never informed of the people who had positive comments, only negative.