Which of the following describes Greek columns that are plain and unadorned?

The description of Greek columns that are plain and unadorned aligns with the Doric order. Doric columns are characterized by their simplicity and lack of decorative elements, making them the most austere of the three classical orders. They typically feature a sturdy, fluted design with a simple capital that is almost flat, reflecting the robustness of the style. This unembellished aesthetic is closely associated with the temples and structures of ancient Greece, particularly those dedicated to male deities, conveying strength and directness in architectural form.

In contrast, the Corinthian order is known for its extravagant capitals adorned with acanthus leaves, while the Ionic order includes volutes (scroll-like ornaments) in its capital and features a more slender profile. The Composite order combines elements from both the Corinthian and Ionic styles, making it more ornate as well. Therefore, the Doric column's emphasis on straightforwardness and minimalism clearly distinguishes it as the correct answer in this context.