A company wants to predict sales based on advertising spending using a regression model. They collect data for 10 months and find a strong positive linear relationship. However, they only advertised heavily in months with high seasonal demand. What is the primary limitation of using this model to predict sales for a month with low seasonal demand?

✓ Correct Answer: Option C

The observed relationship between advertising and sales is confounded by seasonal demand. The model was trained under specific conditions (high advertising during high demand). Applying it to low seasonal demand, where advertising patterns might differ or have a different effect, would be extrapolation outside the data's relevant domain and likely unreliable.