When should an advertiser consider using bid modifiers?

The correct answer is When they have additional data not available to Amazon DSP that informs the value of impressions because bid modifiers are most useful when advertisers have external data that can provide further insight into the value of certain impressions. For example, if an advertiser knows that specific audience segments, locations, or times of day are more valuable to their campaign, they can use bid modifiers to adjust bids accordingly. This allows for more refined targeting based on factors beyond what Amazon DSP automatically considers. The other options are less relevant because bid modifiers are typically used to enhance, not reduce, control over bidding, and they are not necessary when Amazon DSP is already optimizing bids for standard campaign goals.