The drinking age should remain at 21 years of age. Prior to reaching the age of 21, the brain is not fully developed. As a result, people cannot make informed decisions about alcohol, and the abuse of alcohol can lead to severe brain damage. Which one of the following, if true, would most weaken the argument's conclusion? ['Making informed decisions about alcohol reduces the risk of severe brain damage.', 'The brain fully develops around 24 years of age.', 'People over the age of 21 spend more money on alcohol than people under the age of 21.', 'Alcohol can cause severe brain damage after the age of 21.']