Final answer:
Option (b), which states that trying teens as adults serves as a deterrent to criminal acts, is not a bottom line message regarding the U.S. justice system's approach to teens; it contrasts with the research suggesting this approach does not deter future criminal behavior.
Step-by-step explanation:
The question asks which statement is not a bottom line message regarding the U.S. justice system's approach to teens. The options are (a) the punitive approach of the U.S. system makes it stand out negatively, (b) trying teens as adults deters criminal acts, (c) trying teens as adults does not deter future criminal acts, and (d) the U.S. justice system has ignored scientific research on the adolescent brain. Based on the provided information, the systems of justice in the U.S. are frequently criticized for punitive measures, such as mass incarceration and trying juveniles as adults, which may not align with effective deterrents or rehabilitation strategies. Therefore, the exception, or the statement not in line with bottom line messages, is option (b) stating that trying teens as adults serves as an effective deterrent to criminal acts. This statement is in stark contrast to current research and reports that suggest otherwise.