Currently, the number of first-time admissions of individuals diagnosed as manic-depressives to hospitals in Great Britain exceeds by nine times the number of admissions of such patients to public and private hospitals in the United States, even though the population size of the United States is many times that of Great Britain.
Which of the following, if true, would be most useful to an attempt to explain the situation described above ？（）

A．The term manic-depressive refers to a wider range of mentally ill patients in Great Britain than it does in the United States.

B．The admission rate in the United States includes those individuals who visit clinics for the first time as well as those who are admitted directly to hospitals.

C．A small percentage of patients diagnosed as manic-depressive in Great Britain are admitted to private nursing homes rather than hospitals.

D．The variety of training institutions in psychology in the United States is greater than in Great Britain, reflecting the variety of schools of psychology that have developed in the United States.

E．Seeking professional assistance for mental health problems no longer carries a social stigma in the United States, as it once did.

防水混凝土主要满足强度要求，其次要满足抗渗要求。