An unknown white powder is tested by an antibody based detection system. The test does not indicate the presence of anthrax, yet the sample did contain B. anthracis spores. This is an example of:

A. Sampling error

B. A false positive

C. A false negative

D. A neutral error

Answer: The correct answer is option C.

Explanation:

A false negative test is a diagnostic error in which a test shows absence of a disease even when a person is having a disease.

Similarly, in the given question a sample has anthrax spores; however, antibody test fails to show the presence of anthrax. Thus, it is a false negative.

In contrast, false positive error is the error in which the test shows the presence of disease even when a person is not suffering from it.

Sampling error is a statistical error.

Thus, the correct answer is option C.