Explanation:

You have press releases stored as PDF files. The task involves two parts:
Extract text
The correct service for OCR and text extraction from images and PDFs is Azure Computer Vision (specifically, the OCR and Read API).
While Form Recognizer can also extract text, it is primarily used for structured documents like invoices, receipts, or forms. Since the documents here are press releases (unstructured text), the best service is Computer Vision.
Perform sentiment analysis
Sentiment analysis falls under natural language processing (NLP).
The correct service is Azure AI Language (Text Analytics API).
It provides sentiment analysis, opinion mining, key phrase extraction, entity recognition, and more.
Why not other options?
Azure Cognitive Search is used for search indexing, not OCR or sentiment.
Form Recognizer specializes in structured document extraction, not sentiment analysis.
Computer Vision cannot perform sentiment analysis (only visual/text extraction).
The Answer:
Extract text # Computer Vision
Perform sentiment analysis # Language
Microsoft References
Computer Vision Read OCR
Language service - Sentiment Analysis