Which statement best describes the temporality limitation of cross-sectional studies?

• A. They can establish temporality.
• B. They are best for rare outcomes.
• C. They require long follow-up.
• D. They measure prevalence at a single point in time, so temporality cannot be established.

Answer: (D)

Temporality means whether the exposure comes before the outcome. A cross-sectional study captures exposure and disease status at the same moment, giving a single snapshot. Because both are measured together, you can’t tell which came first, so you can’t establish that the exposure preceded the outcome. This is why measuring prevalence at a single point in time inherently limits the ability to infer temporal sequence. The design isn’t about following people over time to see who develops what, so it isn’t suited to determine causality based on time order.