Zookeeper: Big cats are undoubtedly among the smartest land mammals. Lions, tigers, and jaguars immediately adjust to their new surroundings. Other animals refuse to eat or drink in captivity, but the big cats relish their timely prepared meals. Big cats never attempt to escape their enclosures. Which one of the following, if true, most weakens the zookeeper's argument? ["Big cats don't attempt to escape because they can't figure out their enclosures' weak spots.", 'No qualified expert believes that adjusting to captivity is a measure of intelligence.', 'Bears also do not have any trouble adjusting to captivity.', 'A recent study comparing the brain scans of large mammals revealed that big cats exhibit the most brain activity when stimulated.']