The deployed permission set will merge with the existing permission set in production, meaning changes made in the sandbox will be added to the existing permission set after deployment. Reference:
Salesforce Help - Permission Sets

Explanation
The solution that the app builder should configure to meet these requirements is creating three lead record types each with its own page layout containing the relevant fields. This way, the app builder can customize the fields and sections that appear on each record type based on the source of the lead. Option B is incorrect because creating a partner community and a record type for web and trade show leads does not address the requirement of collecting information that is unique to each type of lead, as partner community users may have different fields and layouts than internal users. Option C is incorrect because creating three sections on the lead layout and instructing users to collapse the non-relevant fields does not address the requirement of collecting information that is unique to each type of lead, as users may still see or enter data in the wrong fields. Option D is incorrect because creating custom page layouts for each type of lead only containing the relevant fields does not address the requirement of collecting information that is applicable to all sources, as users may miss some common fields.