A seal takes four dives, and you are measuring the oxygen consumption rate (ml/(g min) by flow-through respirometry. The flow rate through the chamber is kept constant at 20 liters/min. For all dives, the expired oxygen fraction you measured was 0.15. Here are the dive durations: first dive: 10 min
second dive: 12 min
third dive: 15 min
fourth dive: 20 min

During which dive did the seal consume oxygen at the highest rate?

a. second dive
b. fourth dive
c. third dive
d. first dive