Final answer:
The task mentioned in the sentence is labeling images.
Step-by-step explanation:
The task mentioned in the sentence "Please label the images to review the process of polymerase chain reaction and how its products can be analyzed using gel electrophoresis" is labeling images. The sentence specifically asks for the images to be labeled to review the process of polymerase chain reaction (PCR) and the analysis of its products using gel electrophoresis.