Final answer:
Feeling guilty could lead to reckless decisions that compromise the safety and mission of an operative. This can be paralleled to the historical context of espionage, where emotions must be managed carefully to avoid endangering oneself and the mission.
Step-by-step explanation:
The question "Why was it too dangerous to let Keefe feel guilty?" suggests a scenario from a narrative or fictional context rather than a real-life historical event. Nonetheless, taking into account the nature of espionage and intelligence operations as seen in historical incidents like the U-2 Affair, we can infer why feeling guilty or showing signs of distress can be dangerous for an operative.
Feeling guilty or conveying a sense of guilt could be detrimental as it may lead to reckless decisions, which could exacerbate already dangerous situations or result in the capture of the operative by the enemy. In the options provided, c) "Keefe is prone to making reckless decisions when guilty" seems to be a likely reason.
If an operative makes reckless decisions due to guilt, it can compromise their mission and potentially lead to their capture or the revelation of sensitive information to adversaries. Emotions can be a liability in high-stakes situations where clear-headed decision-making is essential for maintaining safety and operational security.