Where in the settings can a brand change the currency for their advertising account?

The correct choice is C, which refers to Ad account settings, where a brand can change the currency for their advertising account. This area is specifically designed to manage various details of the ad account, including financial configurations such as the currency used for billing and reporting.

Ad account settings allow brands to select the currency that reflects their financial operations best, which is crucial for budgeting and monitoring advertising expenses. Once the currency is set in this section, it affects how costs are displayed on the advertising platform, ensuring clarity in financial management.

Other settings, such as profile settings, business settings, and payment methods, do not provide the option to change the currency. Profile settings focus on user account details, business settings manage overall business-level preferences and configurations, and payment methods are related to how payments are processed rather than the currency in which they are displayed or calculated.