Investment losses are typically classified as non-default-related risks for central counterparties (CCPs). CCPs often use the funds they hold on margin to generate profits and interest. These margin funds can be composed of both cash and securities. However, the value of these securities can fluctuate, sometimes decreasing in value, which can lead to investment losses. Therefore, investment losses are not directly related to default but are a result of the investment decisions made by the CCPs. This makes investment losses a non-default-related risk.

It's important to note that while investment losses can indirectly lead to default if they are significant enough, they are not a direct result of a default event. Instead, they are a result of market movements and investment decisions, which are separate from the creditworthiness of the CCP's counterparties. Therefore, investment losses are considered a non-default-related risk.

Choice A is incorrect. A failed auction is a default-related risk. When a clearing member defaults, the CCP may use an auction process to transfer the defaulter's positions to other members. If this auction fails, it can lead to significant losses for the CCP.

Choice C is incorrect. The resignation of clearing members can also be considered as a default-related risk. Clearing members are responsible for fulfilling financial obligations in case of a counterparty's default. If they resign, it could potentially increase the risk of default and cause instability in the system.

Choice D is incorrect. Reputational risk might not directly relate to defaults but it can be triggered by them or their mishandling by CCPs which makes it indirectly related to default risks.