Which statement about evidence in an assurance engagement is true?

In the context of an assurance engagement, sufficiency refers to the measure of the quantity of audit evidence gathered. It indicates the amount of evidence required to support the auditor's conclusions and ultimately their opinion on the financial statements or the subject matter of the engagement. The concept emphasizes that auditors need to collect enough evidence to provide a reasonable basis for their findings, considering the risk of material misstatement or non-compliance.

While relevance is indeed crucial for ensuring that the evidence collected is appropriate to the specific audit or assurance objectives, sufficiency deals specifically with the volume of that evidence, highlighting its role as a quantitative measure. The importance of both relevance and sufficiency is recognized within the framework of auditing standards, but sufficiency directly addresses how much evidence is necessary to reach an acceptable level of assurance.

The other options do not accurately represent the principles governing evidence in assurance engagements. For example, evidence does not need to be conclusive; rather, it should support reasonable conclusions. Additionally, persuasive evidence, while valid, should not be disregarded solely for being less than conclusive, as its adequacy can depend on the circumstances surrounding the engagement.