Task A has the following details：Optimistic estimate=30，pessimistic estimate=40，most likely estimate=35．Task B has the following details：Optimistic estimate=32，pessimistic estimate=37，most likely estimate=34．Task C has the following details：Optimistic estimate=25，most likely estimate=35，pessimistic estimate=45．Which task has the highest standard deviation ？（）
A．Task
B．Task
C．Task
D．Task A & Task
