You have been looking at the actual vs expected defects in one high risk area...

Context Analysis:

Higher-than-expected defects in a high-risk area indicate the need for additional testing to mitigate potential impacts.

Evaluation of Options:

A. Reassess the risk with a higher likelihood number:

Incorrect. While reassessment is useful, immediate action should prioritize more testing.

B. Reassess the risk with a higher impact number:

Incorrect. The impact may already be known, and more testing is the next practical step.

C. Concentrate more testing in the area because the risk is clearly higher:

Correct. Addressing higher-than-expected defects through focused testing ensures risks are adequately mitigated.

D. Concentrate less testing in the area because the defects are already found:

Incorrect. Higher defects warrant more testing, not less.

Syllabus Alignment:

ISTQB highlights increasing test efforts in high-risk areas with higher-than-expected defect levels (TM-1.3.4).

References:

ISTQB Advanced Level Test Management Syllabus (TM-1.3.4)​