回答下列各题 One of the most interesting paradoxes in America today is thatHarvard Univers

ity，the oldest institution of higher learning in the United States，is UOW engaged in a serious debate about what a university should be，and whether it is measuring up(符合标准)．Like the Roman Catholic Church and other ancient institutions，it is asking--still in private rather than in public--whether itspast assumptions about faculty，authority，admissions，courses of study，are really relevant to the problems of our society． Should Harvard or any other university—be an intellectualsanctuary，apart from the political and social revolution of the age，or should it be a laboratory for experimentation with thesepolitical and social revolutions；or even an engine ofthe revolution This is what is being discussed privately in the bigclapboard(楔形板)houses of faculty members around theHarvard Yard． The issue was defined by Walter Lippmann，a distinguished Harvard graduate，many years ago． “If the universities are todo their work，”he said，“they must be independent and they mustbe disinterested…They are places to which men can turn for unbiased judgments．Obviously，the moment the universities fallunder political control，or under the control of privateinterests，or the moment they themselves take a hand inpolitics and the leadership of government，their valueas independent and disinterested sources of judgment is impaired…” This is part of the argument that is going on at Harvard today．Another part is the argument ofthe militant and even many moderated students：that auniversity is the keeper of our ideals and morals，andshould not be“disinterested”but activist in bringingthe Nation’s ideals and actions together． Harvard’s men of today seem more troubled and less sure aboutpersonal，political and academic purpose than they did at the beginning．They are not even clear about how they should debate and resolvetheir problems，but they are struggling with themprivately，and how they come out is bound to influenceAmerican university and political life in the 21st century． A "paradox"(Line 1, Paragraph 1) is __________.

A.an unusual situation

B.a difficult puzzle

C.a parenthetical expression

D.a self-contradiction