In an experiment, volunteers have to remember a series of words appearing on the screen, but they will be interrupted by occasional math problems. Researchers will periodically ask volunteers whether they are distracted, and finally, remember the number of words Scoring volunteers' "brain running capacity". The results show that those who are stunned when there are math problems remember more words, proving that they have a larger "brain running capacity". Researchers believe that those who often score God, the crazed ones are actually smarter because they can memorize a lot of information and use it flexibly. Which of the following, if true, cannot weaken the experimental conclusion? ['In life, most of the time the brain is distracted when doing anything, usually unnoticed.', 'The math problem is changed to a reading comprehension problem, but the number of words remembered by the volunteers is less.', 'Brain operating capacity is also related to other indicators of human IQ, not just the number of words.', 'Only when the task is not difficult, a person with a large brain capacity will think about unrelated things.']