A clean build puts the rule where Salesforce evaluates it. Choose A. Make the Opportunity type a required field on the initial Opportunity page layout and Use automation to update the record type based on the Opportunity type. The requirement in the stem is: An app builder wants to limit the amount of fields users see When creating a new Opportunity. Once they fill out the required fields and Save, the full record page with additional fields relevant to the Opportunity Type. The selected option addresses that requirement at the point where Salesforce actually evaluates the behavior.
The underlying concept is Lightning page configuration. Lightning App Builder controls page composition, component visibility, activation, assignments, and specialized surfaces such as record pages, home pages, and utility bars. That is why this answer is more defensible than a workaround. It can be reviewed in Setup, included in the correct deployment path, and tested by impersonating or logging in as a representative user where appropriate.
The remaining answers do not control the same Salesforce behavior. B (Use different page layouts for Opportunity types based on the user profile.) does not fit cleanly; Page layouts affect presentation; they do not grant the underlying object or field capability by themselves. C (Once the required fields are populated, use a sharing rule to share the new fields with The user.) is only a partial match because Sharing controls record visibility; it does not change field type, page composition, or automation timing. D (Hide additional sections on the page layout and the users how to manually Expand them when they want to fill in the fields in the hidden sections.) misses the mark because Page layouts affect presentation; they do not grant the underlying object or field capability by themselves. The result is a cleaner app design because the behavior is handled by the feature Salesforce built for that purpose.
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