On-Demand Email-to-Case is a feature that allows you to automatically create cases from customer emails without installing any software on your email server. It uses an email service provided by Salesforce to convert emails into cases and route them to the appropriate queues or agents. This solution meets the IT policy of Universal Containers, as it does not require any third-party software installation. Verified References: On-Demand Email-to-Case

Explanation
A web-to-case question is a solution that can automate the use of suggested articles to deflect customer's interaction with a support agent while still providing relevant answers to the customer. It allows customers to submit cases from a company's website and receive suggested articles based on their question before submitting the case. Verified References: :
https://help.salesforce.com/s/articleView?id=sf.knowledge_web_to_case_deflection.htm&type=5 :
https://help.salesforce.com/s/articleView?id=sf.knowledge_web_to_case_overview.htm&type=5

A Lightning email template is a type of email template that can be used to create and send emails from Salesforce. A Lightning email template can include merge fields, images, links, and other formatting options.
A Lightning email template can also include a knowledge article as an attachment or a link. A consultant can configure a Lightning email template to send the article to the customer by selecting the Knowledge Article option in the template editor and choosing the article to include. The agent can then use the template to send an email with the article to the customer from the case record page or the Service Console. Verified References: Service Cloud Consultant Certification Guide & Tips, Create Lightning Email Templates

A sharing set is a feature that allows community members to access records that are not owned by them or shared with them by the org-wide default settings. A sharing set can grant access based on a common lookup field, such as the contact field on the case object. By setting up a sharing set to grant access based on the site member's contact record, the consultant can enable community members to access, create, and manage cases online. Verified References: Service Cloud Consultant Certification Guide & Tips, Sharing Sets Overview