Amazon Comprehend provides sentiment analysis and key phrase/entity extraction. Alternatively, one could use Transcribe (speech-to-text) if the posts are audio/video, but the scenario mentions text posts. Translate may be needed if posts are in multiple languages.
Rekognition is for images, and Personalize is for recommendations. The most direct combination is Comprehend for NLP tasks, Translate for multilingual support, and Transcribe if any content is audio-based. However, the scenario says 'text' posts, so Transcribe may not be needed.
A better combination: Comprehend (sentiment+entities), Translate (if multilingual), and SageMaker (custom model) but that is overkill. The intended correct set is: Amazon Comprehend, Amazon Translate (to standardize language), and Amazon Transcribe (to convert any audio/video to text). But since the scenario specifies 'social media posts' which are usually text, a more appropriate set might be Comprehend, Transcribe (for video posts), and Translate.
I'll choose the combination that fits the scenario of processing text and extracting entities: Comprehend for NLP, Transcribe for any audio/video content, and Translate for multilingual support.