What Is the Major Disadvantage to the Fluorescence in Situ

What is the major disadvantage to the fluorescence in situ hybridization (FISH) method of genetic testing?

A) Single-nucleotide mutations cannot be detected.
B) Depending on the skill of the technician, the rate of false positives is high.
C) The sample for testing must be obtained from living tissue rather than from a preserved specimen.
D) Results are not available quickly because cells must first be grown in culture before testing can be performed.