Answer: The correct answer is option C.
Step-by-step 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.