In the following question, a sentence/a part of the sentence is bold. Four alternatives are given to the bold part which will improve the sentence. Choose the correct alternative and mark corresponding to it. In case no improvement is needed, mark corresponding to No improvement.
They were all astonished at the team's dramatic success in the competition.

• were astonished at all

• had all astonished by

• had been all astonished on

• had been all astonished on