Improve the bracketed part of the sentence. He jumped off the train while it (had been running) .1). has been running2). ran3). was running4). No improvement

Improve the bracketed part of the sentence. He jumped off the train w

1.	Improve the bracketed part of the sentence. He jumped off the train while it (had been running) .1). has been running2). ran3). was running4). No improvement
Answer» ANSWER for this QUESTION is RAN