During a microarray analysis, cDNAs made from normal cells are stained with a green fluorescent label and cDNAs from abnormal cells are stained with a red fluorescent label. Which of the following statements best summarizes the results of this experiment?

A) Red spots indicate genes that are underexpressed in abnormal cells.
B) Red spots indicate genes that are not expressed in abnormal cells.
C) Red spots indicate genes that are overexpressed in abnormal cells.
D) Red spots indicate genes that are overexpressed in normal cells.