These are two capabilities that My Domain enables in the context of a SAML SSO configuration. My Domain is a feature that lets you customize your Salesforce domain name and login page1. Resource deep linking is the ability to access a specific page or resource within Salesforce directly from a link, without having to navigate through the app2. SSO from Salesforce Mobile App is the ability to log in to the Salesforce Mobile App using your SSO credentials, without having to enter your username and password3. My Domain enables these capabilities by allowing you to specify your identity provider (IdP) and SSO settings for your unique domain name, and by providing a custom login URL that can be used for deep linking and mobile app login1. The other options are notcorrect for this question because:

App Launcher is a feature that lets you access all your connected apps from one place in Salesforce. It does not require My Domain or SAML SSO to work, although it can be enhanced by using them.

Login Forensics is a feature that analyzes login behavior and identifies anomalous or suspicious logins. It does not require My Domain or SAML SSO to work, although it can be used with them. References: MyDomain, Deep Linking into Salesforce, Salesforce Mobile AppBasics, [App Launcher], [Login Forensics]