When it was created at the end of the second world war, the International Bank for Reconstruction and Development had been given the clear purpose of helping to finance the rebuilding of war-torn Europe.
(A) When it was created at the end of the second world war, the International Bank for Reconstruction and Development had been given the clear purpose of helping to finance.
> use of past participle is not correct, as it is used to refer deeper past and here there is no such comparison of time.
(B) When it had been created at the end of the second world war, the International Bank for Reconstruction and Development had been given the clear purpose of helping to finance.
> Issue with use of past participle.
(C) When it was created at the end of the second world war, the International Bank for Reconstruction and Development had been given the clear purpose of helping the financing of
> Same issue as above.
(D) Created at the end of the second world war, the International Bank for Reconstruction and Development had been given the clear purpose of helping to finance
> It is not like that the bank had already been given purpose, before it was created. So use of past participle is wrong.
(E) When it was created at the end of the second world war, the International Bank for Reconstruction and Development was given the clear purpose of helping to finance
> Correct choice.