Which textual factors are known to affect comprehension?

The correct choice highlights critical components that significantly influence reading comprehension. Word identification is fundamental as it refers to the ability to recognize and understand words, which directly impacts one's capacity to comprehend text. If a reader struggles with identifying words, their overall understanding of the material will be compromised.

Background knowledge is another crucial factor. This refers to the information and experiences a reader brings to a text. A reader with relevant background knowledge will have an easier time relating to the content, making connections, and integrating new information, thereby improving comprehension.

Visual displays encompass elements like graphs, charts, or illustrations that can provide additional context and aid understanding. Effective visual aids can enhance the reader’s ability to grasp complex ideas or see relationships between concepts, further supporting comprehension.

While the other options contain elements that may influence comprehension, they don't encompass the foundational aspects as clearly as this choice. For instance, contextual relevance and personal interest (present in another choice) are significant, but they rely heavily on the reader's background knowledge and vocabulary skills. Similarly, schema activation and fluency are vital but are often built upon the skills mentioned in the correct choice.