In computer graphics and user interfaces, the rectangular boundary drawn around a selected or specific area on the display is called:

Introduction / Context:
Graphical systems segment the display into regions for organization, interaction, or rendering control. The common term for a rectangular region used to present content or select an area is “window.” This concept underlies window managers, clipping, and viewport transformations.

Given Data / Assumptions:

• We are discussing 2D screen regions with rectangular boundaries.
• Interactive systems may highlight selection with a marquee rectangle.
• Rendering pipelines map world coordinates into viewports/windows for display.

Concept / Approach:
A window is a rectangular area on-screen that can display content and accept input. In graphics terminology, a “window” (world-space selection) and “viewport” (device-space mapping) both involve rectangular bounds; everyday UI uses “window” for application panels.

Step-by-Step Solution:
1) Identify the artifact: a rectangular boundary enclosing an area. 2) Map to UI/graphics vocabulary: this is a window/viewport region. 3) Eliminate geometry and camera terms that do not denote a UI rectangle to users.

Verification / Alternative check:
HCI and graphics references consistently label such on-screen rectangular regions as windows (and viewports in rendering contexts).

Why Other Options Are Wrong:
Option B: Conic sections are geometric curves, not UI regions.
Option C: A viewpoint is an observer position, not the rectangle itself.
Option D: A view plane is an abstract plane in 3D rendering, not the on-screen rectangle.

Common Pitfalls:
Confusing “window” with “viewport”; both are rectangles, but UI usage typically says “window.”

Final Answer:
A window