Final answer:
The circumstances that would lead a reasonable prudent professional to believe fraud has occurred, is occurring or will occur are referred to as evidential circumstances.
Step-by-step explanation:
The correct answer is a. Evidential circumstance. Evidential circumstance refers to the circumstances, taken as a whole, that would lead a reasonable prudent professional to believe fraud has occurred, is occurring or will occur. It involves gathering and analyzing evidence to determine if there are indications of fraud. For example, if there are irregularities in financial records, unexplained discrepancies, or suspicious transactions, these can be evidential circumstances that suggest fraud.