The comparable uncontrolled price method compares the price charged in a controlled transaction with the price charged in a comparable transaction between independent parties. Its major limitation is finding a sufficiently comparable uncontrolled transaction. Differences in product quality, contract terms, geography, volume, timing, market conditions, risks, and functions can make comparison difficult. Option B may describe a general risk of transfer pricing systems but is not the common CUP limitation. Option C is incorrect because adjustments may be possible if differences can be reliably measured. Option D is wrong because CUP is usually a direct method for identifying an arm's-length price. Internal auditors reviewing transfer pricing should assess comparability, documentation, assumptions, and regulatory compliance.
Therefore, Option A is correct.