question: What was the cause of the period of turmoil prior to the announcement that the Shell Group would move to a single capital structure ?
answer: the revelation that Shell had been overstating its oil reserves
turker_answer: The cause of the period of turmoil prior to the announcement that the Shell Group would move to a single capital structure was the revelation that Shell had been overstating its oil reserves .
rule-based: The cause of the period of turmoil prior to the announcement that the Shell Group would move to a single capital structure was the revelation that Shell had been overstating its oil reserves .