Explanation/Reference:
B:
* Content types enable site users to quickly create specialized kinds of content by using the New Item or New Document command in a list or library. Content types provide site owners a way to make sure that that content is consistent across sites. Site owners can pre-configure specific details about the content when they set up content types for a site, list, or library.
* Define content types
If your group works with several types of files, such as worksheets, presentations, and documents, you can extend the functionality of your library by enabling and defining multiple content types. Content types add flexibility and consistency across multiple libraries. Each content type can specify a template and even workflow processes. The templates act as a starting point, for formatting and any boilerplate text and for properties that apply to the documents of that type, such as department name or contract number.
Reference: Best practices for creating and managing team sites
C: To map a master page to a SharePoint site
1. In Site Settings for the designated site, under the Look and Feel section, choose Master Page.
2. On Site Master Page Settings, select one of the two options for the Site Master Page or System Master Page sections:
2a. Inherit site master page from parent site Choose this option if you are configuring a child SharePoint site and want to use the parent master page.
2b. Specify a master page to be used by this site and all sites that inherit from it Choose this option if you want to map a specific master page to the site, or if you want to map a specific master page for administrative pages. A drop-down box named Default or All Channels is available for you, depending on your site or system configuration, so you can select a specific master page stored in the master page gallery. Select the desired master page from the drop-down box.
3. Choose OK.
Reference: How to: Apply a master page to a site in SharePoint 2013
D:
* A Composed Look is made up of:
Master Pages
CSS
Color palettes
Font palettes
Background image
* This means we can package a master page with its CSS, color palettes, font palettes and background image and have it deployed in the enterprise. With Composed Looks, you can now offer your Power Users a list of branded looks and allow them to choose an appropriate look as well as giving them limited control to make changes to the colors, image or font. You could be providing the Composed Looks.
Reference: Step by Step: Create a SharePoint 2013 Composed Look