Explanation
A plugin is a component that extends the native functionality of Oracle APEX by allowing developers to create custom components using SQL, PL/SQL, HTML, CSS, and JavaScript. A plugin can be created for any of the following component types: Dynamic Action, Item, Process, Region, Report Layout, Authentication Scheme, Authorization Scheme, or Data Load Method. A process plugin is a custom process type that can be executed when a page is submitted or loaded. A region plugin is a custom region type that can display data or content on a page. Verified References: [Creating Plugins - Oracle Help Center], [Plugin Concepts - Oracle Help Center]

Explanation
Oracle APEX is a low-code development platform that enables you to build database-centric web applications using only a web browser. Oracle APEX has the following features:
Requires no additional client software. A web browser is the app development IDE: You can use any modern web browser to access the Oracle APEX development environment and build your applications.
You do not need to install or configure any additional software or tools on your client machine.
Is declarative. It requires no code generation: You can use declarative tools, visual editors, drag-and-drop components, and pre-built templates to define your application logic, user interface, security, and integration features. You do not need to write or generate any code for your applications.
The other options are incorrect because:
Performs the data processing in a middle-tier server: Oracle APEX performs the data processing in the database server. It uses SQL and PL/SQL to access and manipulate the data stored in the database. It does not rely on any middle-tier server or framework for data processing.
Requires developers to be proficient in Java, Python and other programming languages: Oracle APEX does not require developers to be proficient in Java, Python or other programming languages. It uses SQL and PL/SQL as the primarylanguages for data processing. It also supports HTML, CSS, JavaScript, and jQuery for user interface development.
Verified References: [About Oracle APEX] [Oracle APEX Architecture]

Explanation
Cards are a page type that display information in a grid layout of tiles. Each card can contain an image, a title, a subtitle, and an optional link. Cards are suitable for presenting summary or overview information in an attractive and compact way1 Verified References: 1: Understanding Page Types, Features, and Settings - Oracle Help Center

Explanation
A Page Computation can be created from two tabs in Page Designer: Rendering Tree and Processing. In the Rendering Tree tab, you can create a Pre-Rendering Computation or a Post-Rendering Computation by right-clicking on these nodes under your page node. In the Processing tab, you can create an After Submit Computation by right-clicking on this node under your page node. Dynamic Actions and Shared Components are not tabs in Page Designer, but sections in Application Builder where you can create other types of components for your application