Credit risk does not fall under the category of risks that are difficult to quantify or not directly attributable to any specific integrated firm-wide risk categories. Credit risk is a well-defined and quantifiable risk that arises from the potential that a borrower or counterparty will fail to meet its obligations in accordance with agreed terms. It is a fundamental risk category that banks face and is directly attributable to their lending and investment activities. Banks have well-established methodologies for quantifying credit risk, including credit scoring systems, credit risk models, and provisions for loan losses. Therefore, credit risk does not fall into the category of 'other risks' that are difficult to quantify or not directly attributable to specific firm-wide risk categories.

Choice A is incorrect. Compliance risk refers to the potential for financial loss, legal penalties, or regulatory sanctions due to non-compliance with laws or regulations. It is a type of risk that is challenging to quantify as it depends on various factors such as changes in regulatory environment, effectiveness of internal controls and so on.

Choice C is incorrect. Reputational risk refers to the potential for negative publicity, public perception, or uncontrollable events that could damage a company's reputation and affect its revenue. This type of risk is also difficult to quantify because it relies heavily on subjective factors like public opinion and media coverage.

Choice D is incorrect. Strategic risk arises from poor business decisions, improper implementation of decisions, or lack of responsiveness to industry changes. This kind of risk can be hard-to-quantify as it involves assessing the impact of indirect factors such as market competition and strategic positioning which are not directly attributable to any specific integrated firm-wide risk categories.