The AI assistant agrees with the suggested answer, D.

Reason for choosing this answer:
The question asks to identify which of the listed "display types" is bidirectional.
USB-C (Universal Serial Bus Type-C) is the only option that is fundamentally designed for bidirectional communication across multiple functions. While it can carry display signals (via DisplayPort Alt Mode, HDMI Alt Mode, or Thunderbolt), its core functionality extends far beyond just video transmission. USB-C supports:

Bidirectional data transfer: Standard USB data (USB 2.0, 3.x, 4) can flow in both directions between the host and device, allowing for devices like monitors to act as USB hubs, sending data from connected peripherals back to the computer.
Bidirectional power delivery: USB-C with Power Delivery (PD) allows power to flow in either direction, enabling a display to charge a laptop, or a laptop to power a portable display, as well as charging other devices connected to the display.
Alternate Modes (Alt Modes): While display signals (video) themselves typically flow unidirectionally from source to display, the USB-C port's ability to simultaneously carry bidirectional USB data and power makes the overall "display type" bidirectional in its utility and communication capabilities. For example, a USB-C monitor can provide power, receive video, and send USB data back to the host all over a single cable.

This comprehensive bidirectional capability for data, power, and multi-role functionality makes USB-C the most appropriate answer.

Reasons for not choosing the other answers:

A. DisplayPort: DisplayPort is primarily a unidirectional digital video and audio interface. While it includes a bidirectional auxiliary (AUX) channel for control signals (such as EDID, MCCS, and DisplayPort Content Protection), the main high-bandwidth video and audio data streams are unidirectional from the source to the display. It does not support bidirectional data for peripherals or power delivery in the same integrated manner as USB-C.
B. VGA (Video Graphics Array): VGA is an older, analog display interface that is strictly unidirectional. It transmits video signals only from the source (e.g., computer graphics card) to the display (monitor). It has no inherent capability for bidirectional data communication or power transfer over the primary display connection. The discussion content's conclusion that B is the correct answer is factually inaccurate regarding bidirectionality.
C. DVI (Digital Visual Interface): DVI is a digital video interface, primarily designed for unidirectional transmission of video signals (and sometimes audio, depending on the implementation) from a source to a display. Similar to VGA and DisplayPort, it uses a separate DDC (Display Data Channel) for bidirectional EDID (Extended Display Identification Data) communication, but the main video data path remains one-way. It lacks the inherent bidirectional data and power capabilities of USB-C.

The "internet discussion from Q3 2025" mentioned in the discussion summary, which concludes that B (VGA) is the answer, appears to be incorrect. VGA is a purely unidirectional analog interface, whereas USB-C is designed for comprehensive two-way communication of data and power, making it the only truly bidirectional option among the choices.

Citations:

USB-C Explained: What it is, How it works, and Why it matters, https://www.tripplite.com/products/usb-c-explained-what-it-is-how-it-works-why-it-matters~10522
What is USB-C and how does it work?, https://www.intel.com/content/www/us/en/docs/next-gen-compute/what-is-usb-c-and-how-does-it-work.html
DisplayPort Technical Overview, https://www.vesa.org/displayport-technical-overview/
DisplayPort vs. HDMI vs. DVI vs. VGA, https://www.monitornerds.com/displayport-vs-hdmi-vs-dvi-vs-vga/