Understanding Seasonality in Retail Sales Data

In the context of time-series analysis, seasonality refers to periodic fluctuations in a time series that occur at regular intervals due to seasonal factors. An analyst is examining monthly sales data for a retail company that experiences significant seasonal variations due to holiday shopping. The analyst performs a seasonal decomposition of the time series using the additive model. The observed time series data indicates a pattern where sales typically peak in December and drop significantly in January.

Given this context, which of the following statements correctly describes a characteristic of seasonality in this retail sales data?