Which of the following is a common cause of poor reading comprehension?

Unfamiliar vocabulary is a significant barrier to reading comprehension because it can disrupt the reader's ability to grasp the meaning of the text. When readers encounter words they do not understand, it hinders their ability to connect ideas and understand the overall message. A lack of understanding due to unfamiliar vocabulary forces readers to slow down and may lead to confusion or misinterpretation of the material, which ultimately compromises comprehension.

In contrast, while a lack of visual aids may impact comprehension, it is not as universally critical as vocabulary knowledge. Background knowledge can actually enhance understanding, and high levels of interest can motivate readers to engage more deeply with the material, making comprehension easier. Thus, unfamiliar vocabulary stands out as a pervasive issue that affects almost all readers, particularly in complex texts.