Approximately how long does S phase take to occur in these cells? (A) 15 min (B) 20

Question:

Approximately how long does S phase take to occur in these cells?
(A) 15 min
(B) 20 min
(C) 30 min
(D) 40 min

An experiment is performed to evaluate the amount of DNA present during a complete cell cycle. All of the cells were synced prior to the start of the experiment. During the experiment, a fluorescent chemical was applied to cells, which would fluoresce only when bound to DNA. The results of the experiment are shown above. Differences in cell appearance by microscopy or changes in detected DNA were determined to be phases of the cell cycle and are labeled with the letters A-D. DNA (Normalized Fluorescent Units) 0 0 A 40 B 1 I 80 Time (min) C I DI T 120 A