Children whose biological parents both have Tic Syndrome Z（TSZ), which is characterized by

Children whose biological parents both have Tic Syndrome Z(TSZ), which is characterized by the involuntary contraction of certain muscles, are about four times more likely to develop such contractions than are children whose biological parents do not have TSZ. It is likely, therefore, that predisposition to TSZ is an inherited trait. Which of the following, if true, would most strengthen the conclusion above？

A．Children whose parents have TSZ are more likely to develop TSZ if they are under unusual stress at school or at home than if they are not under such stress.

B．Children whose biological parents do not have TSZ are more likely to develop TSZ if they are raised by adoptive parents with TSZ than if they are raised by their biological parents.

C．Children whose biological parents have TSZ are as likely to develop TSZ if they are raised by adoptive parents who do not have TSZ as if they are raised by their biological parents.

D．Children whose biological parents have TSZ and who develop TSZ usually avoid developing a severe form. of the syndrome if they seek treatment for TSZ shortly after developing the first signs of it.

E．Children with TSZ whose biological parents do not have TSZ are less likely to have the syndrome diagnosed when symptoms first appear than are children with TSZ whose biological parents have TSZ.