Which forward observer control option requires the FO to contact the FIST for each call for fire?

The control option that requires the forward observer (FO) to contact the Fire Support Team (FIST) for each call for fire is known as the Centralized option. In this control method, the FO does not have the authority to execute fire missions independently; instead, they must relay their requests for fire support through the FIST. This approach ensures that there is a centralized command structure overseeing the fire support process, allowing for better coordination and control of assets.

Centralized control is particularly important in complex operations where multiple fire support assets could be engaged, as it reduces the risk of fratricide and enhances the effectiveness of fire support. The FIST acts as the coordinating body, managing communications and ensuring that the right assets are allocated appropriately.

In contrast, the Decentralized and Designated options provide more autonomy to the FO, allowing them to call for fire without needing to contact the FIST for every request. This makes those options suitable for scenarios requiring rapid and immediate response to the changing battlefield situation but may lack the level of oversight seen in the Centralized option. Hence, the correct answer is focused on the necessity for communication with the FIST for each fire request, emblematic of the centralized control method.