Concept:A possible effect must be a direct and immediate consequence of the given cause.
Explanation:The cause is a major train accident at Katpadi Junction involving the derailment of seven bogies of G.T. Express, blocking the tracks.
Effect I states that many trains on the Katpadi–Chennai route are running late today.
This is a direct result of the derailment, as the accident would disrupt train movement on that route.
Effect II mentions long queues at railway ticket booking counters in Bangalore.
This is not a definite consequence of the accident, because the accident does not directly explain why passengers in Bangalore would queue up at booking counters.
Effect III talks about running holiday special trains between Kolkata and Patna from October to December 2023.
This is completely unrelated to the train accident at Katpadi Junction.
Therefore, only Effect I can be considered a possible effect of the given cause.
Answer:Only I is a possible effect.
Hence, the correct answer is Option B.