The evidence that a child with blood pressure higher or lower than the norm would tend to retain the same blood pressure pattern with increasing age is introduced by the author in order to ______.
A．suggest that essential hypertension may have biochemical causes
B．show that high blood pressure can be detected in children under the age of 15
C．provide evidence that factors affecting blood pressure are already present in children
D．propose that increased screening of children for high blood pressure should be undertaken