Which security monitoring data type requires the most storage space?

Full packet capture is the correct answer because it involves storing every packet of data transmitted over a network during a given time period. This process generates a comprehensive snapshot of all the network traffic, including all headers and payloads, resulting in a significant volume of data. Each packet can vary in size, and since network traffic can be highly variable and potentially very high in volume, the storage needs can scale dramatically with the amount of traffic.

In contrast, transaction data consists of records that capture specific interactions or transactions but do not require storing every single packet. Statistical data typically summarizes events or traffic patterns without necessitating detailed packet information, thus requiring minimal storage. Session data involves capturing the context of connections and interactions between systems which, while more data-intensive than statistical information, is still less comprehensive than full packet capture. Therefore, among these options, full packet capture demands the most storage space due to its detailed and exhaustive nature.