You need to train the Form processing AI model. 
Please select the three process steps for Form processing model training.

Answer options:

A.Tag documents
B.Group documents by their type
C.Choose information to extract
D.Select a domain
E.Create documents collections

Correct Answers: A, C and E 
AI Builder provides several prebuilt Machine Learning cognitive models that users can use in their Power Platform products. AI Builder model list includes models like prediction, object detection, form processor, text classification, category classification, entity extraction, etc. If your business needs do not match the out-of-box models, you can train your models based on your data. 
AI Builder Form processing model is a computer vision model that extracts text from the image. Businesses use this model to automate the data extraction from the standard documents, like invoices or tax documents. 
When you select to create a Form Processing model option from the AI Builder screen and provide the model’s name, a new screen will open. On this screen, you will follow the steps for preparing a model for training. 
The three process steps are: Choose information to extract — you need to create tags for fields you want to extract from the documents.
Add collections of the documents — you need to create the collections and upload similar documents (with the same layout) to collections. You can make up to 100 collections. After this, you click the Analyze button and wait until the AI builder examines the documents and detects the fields and tables you identified in the previous step.
Tag documents — this is a process of teaching the model how to extract the fields and tables. You need to tag all uploaded documents.
After you tag the documents, you can review your model`s summary and push the button Train on the next step. 

Option B is incorrect because Form processing preparation creates document collections by the similarity in the documents` layouts but not documents groups by the document types.
Option D is incorrect because the Select domain is an operation step for Object detection model training but not for Form processing.
For more information about AI Builder Form processing model training, please visit the below URLs: 

https://docs.microsoft.com/en-us/learn/modules/get-started-with-form-processing/
https://docs.microsoft.com/en-us/ai-builder/create-form-processing-model
https://docs.microsoft.com/en-us/ai-builder/form-processing-train