Which of the following audiences can be built from advertisers’ existing audiences, and leverage machine-learning algorithms to help reach new audiences with similar characteristics?

The correct answer is Lookalike audiences because this audience type is specifically designed to identify and target new customers who share similar characteristics with an advertiser's existing audiences. By leveraging machine-learning algorithms, lookalike audiences analyze data from current customers to find individuals who exhibit comparable behaviors, interests, and demographics. This allows advertisers to expand their reach effectively while maintaining relevance. In contrast, Amazon audiences are predefined by Amazon's own data and targeting options, while demographic audiences focus solely on measurable characteristics like age and gender, making lookalike audiences the most effective choice for building upon existing customer insights to find new potential customers.