There is（）difference between tuition rates in public and private institutions of higher learning.

A.they are more likely to represent public interests
B.they have more commonsense and less professional bias
C.their interests are affected by board decisions
D.None of the above

A.research universities
B.doctoral universities
C.A and B and some specialized institutions
D.Both A and B

A.four
B.five
C.six
D.seven