A physician orders a real-time PCR (polymerase chain reaction) DNA detection test on a client experiencing severe diarrhea following IV antibiotic administration. Which of the following statements is the reason for this diagnostic test?

a) PCR is an indirect means of identifying infectious agents by measuring serum antibodies.
b) PCR is effective in determining the diagnosis of Clostridium difficile.
c) PCR allows for rapid enhanced diagnosis using an artificial growth media.
d) PCR allows direct visualization of an infectious agent without the use of a microscope.