Spending a child in a nursery in the first year after birth can cause anxiety. In our study, 464 children aged 12-13 years were tested by the Scenario Specific Test, which is intended to test The relationship between children's condition at the age of 1 and their attachment to their mothers. As a result: 41.5% of children who had been nursed in a nursery and 25.7% of children who had been nursed at home were considered nervous and overly attached to their mother. Which of the following, if true, is least likely to challenge the inferences of the above studies? ['Most children who are cared for at home in the first year after birth are cared for by grandparents or grandparents, and form a strong relationship.', 'The host of this study was proven to have been left out of nursery aunts for too long in their early childhood.', "Another study of children's mothers found that because children show excessive attachment at home, parents want to send them to a nursery for correction.", 'The children tested in the study were not randomly selected from both nursery and home care. Therefore, the families of these two sample children are likely to have systematic differences.']