A recent study pointed out: "Eating seabuckthorn fruit regularly is good for children's intellectual development. " Researchers surveyed 560 children and found that children who regularly eat seabuckthorn fruit have a lower intelligence level than children who rarely eat seabuckthorn fruit Gao. Therefore, researchers have found a link between sea buckthorn fruits and children's intellectual development. Which of the following, if true, is the least likely to weaken the above argument? ['Studies of adults have found that people who eat sea buckthorn fruit daily have no higher intelligence levels than people who rarely eat sea buckthorn fruit.', "The survey shows that the price of seabuckthorn fruit is very high, and only children from rich families often eat it. At the same time, these families have the conditions to achieve children's early intellectual development.", 'The head of this child development study is a seabuckthorn fruit producer, whose purpose is to expand the sales channel of seabuckthorn fruit.', 'Hippophae rhamnoides is food that children like, and parents often give seabuckthorn fruit as a gift to children with excellent intellectual performance.']