Explanation
Step 1: Analyze the immediate cause of J
The rule states: "J occurs only if E or F occurs."
This means for J to happen, at least one of these two (E or F) must have occurred.
Step 2: Trace E and F back to their origins
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If E occurred: The rule says "E occurs only if C occurs." So, C must have occurred.
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If F occurred: The rule says "F occurs only if B occurs." So, B must have occurred.
Step 3: Combine the logic
Since J requires either E or F, it consequently requires either C (the cause of E) or B (the cause of F).
Therefore, for J to occur, it is mandatory that either B or C has occurred.
Why other options are incorrect:
Conclusion:
The occurrence of J guarantees that at least one of the primary branches (B or C) was active.
Correct Option: (b)