Rachel is investigating an information security incident that took place at the high school where she works. she suspects that students may have broken into the student records system and altered their grades. if correct, which one of the tenets of information security did this attack violate? confidentiality integrity availability nonrepudiation

I believe the answer is: Integrity

Information with high integrity tend to let any unathorized person able to alter the information within the system. Compared to other form of violation, violation of integrity had the highest chance of occurrence from direct contact with authorized personnels. (in the sample above, the personnels might the one that provide the students with the key to the computers room)