Which criterion indicates that a decision node construct such as this is well-formed?

Choose the correct answer.

Given the following diagram fragment:

Which criterion indicates that a decision node construct such as this is well-formed?
A . No activity Ai will negate the corresponding guard [gi]
B. Taken together, the guards cover all possibilities and are mutually exclusive.
C. Each guard legal can be evaluated without changing the state of any item referenced by the corresponding activity or action Ai
D. The guards are understandable by stakeholders in the development effort.

Answer: B

Explanation:

A decision node is a construct in SysML that represents a branching point in an activity diagram where alternative paths are chosen based on some conditions. The guards are expressions that specify the conditions for each outgoing edge from the decision node. A criterion that indicates that a decision node construct is well-formed is that the guards cover all possibilities and are mutually exclusive, meaning that for any input value, exactly one guard evaluates to true and all others evaluate to false. This ensures that there is no ambiguity or conflict in choosing the next path in the activity.