The sense of delayed gratification, of working now for later pleasure, has helped shape the economic behavior of our society. However, that sense is no longer nurtured as consistently in our children as it once was. For example, it used to take a bit of patience to put together the toys that children got in cereal boxes; now the toys come from the boxes whole.

Which of the following is an assumption of the passage above?

【选项】The toys in cereal boxes have changed partly because the economic conditions of our society have improved.