Why Should Laboratory Professionals Look for Contamination of a Specimen

Why should laboratory professionals look for contamination of a specimen by normal microbial florae?

A) Contaminated specimens will have much amorphous debris that also goes with them.
B) Normal florae always preclude the possibility of a pathogen infecting the area where they reside.
C) The normal florae will be found in clumps, and any pathogenic bacteria will be found with the normal florae.
D) Contamination of specimens with normal florae that are not collected from sterile sites diminishes the value of the culture studies.