Explanation
The consultant should recommend an app on the AppExchange to create a declaratively configured, public-facing form that creates data in Salesforce, such as FormAssembly or Formstack, which are web form builders that integrate with Salesforce. Process Builder is a tool that automates business processes based on certain criteria or actions, not a form builder. Email-to-case is a feature that converts emails from customers into cases in Salesforce, not a form builder. References:
https://appexchange.salesforce.com/appxStore?type=Product&keywords=form
https://help.salesforce.com/s/articleView?id=sf.process_overview.htm&type=5