Choice "C" is correct. Because computer-related fraud often involves unauthorized access to systems and/or data, review of system access logs is the most likely of these choices to detect fraud. System access logs are electronic lists of who has accessed or has attempted to access systems or parts of systems or data or subsets of data. Choice "a" is incorrect. Data encryption might keep intercepted data from being understood, but it will not detect fraud.Choice "b" is incorrect. Validity checks might prevent erroneous data from being entered into a system, but they will not detect fraud. Choice "d" is incorrect. Fraud-awareness training would help employees to identify possible fraudulent activity but it is not the most lilely to detect fraud.