What does a boolean guard do in a decision node?

In the context of a decision node, a boolean guard serves a critical role in controlling the flow of a model by evaluating a specific condition to determine which path should be taken. This evaluation is based on the true or false outcome of the boolean condition provided. If the condition evaluates to true, the corresponding outgoing flow is activated; if false, that particular path is bypassed. This mechanism effectively dictates how the process branches, leading to different outputs based on the state of the boolean expression, which aligns perfectly with the selection of the first choice.

The other options do not accurately represent the function of a boolean guard within a decision node. While determining the output of the flow is a key aspect, signaling the end of an action pertains more to termination or completion markers rather than decision-making, segregating concurrent flows relates to the management of parallel processes rather than conditional paths, and indicating an active node refers to the current execution status rather than the conditional logic that guides flow direction.