Films for children that _______________ inspiring and adventurous seem to have lost their innocence.
used to be
had to be
were used to be
were to be

Films for children that WERE USED TO BE inspiring and adventurous seem to have lost their innocence.

Films for children that were to be inspiring and adventurous seem to have lost their innocence.

Films for children that used to be inspiring and adventurous seem to have lost their innocence.