21.请阅读Passage 1，完成第1～5小题。 　　Passage 1 　　In re

[单选题]21.请阅读Passage 1，完成第1～5小题。 　　Passage 1 　　In recent years,however,society has come to understand the limitations of schools that merelysort and rank students.We have discovered that students in the bottom one-third to one-half of therank order-plus all who drop out before being ranked-fail to develop the foundational reading,writing,and mathematical proficiencies needed to survive in,let alone contribute to,an increasingly technically complex and ethnically diverse culture.So today,in asking schools to leave no childbehind,society is asking that educators raise up the bottom of the rank-order distribution to aspecified level of competence.We call those expectations our“academic achievement standards”.Every state has them,and,as a matter of public policy,schools are to be held accountable formaking sure that all students meet them. 　　To be clear,the mission of sorting has not been eliminated from the schooling process.Forthe foreseeable future,students will still be ranked at the end of high school.However,society nowdictates that such a celebration of differences in amount learned must start at a certain minimumlevel of achievement for all. 　　The implications of this change in mission for the role of assessment are profound.Assessmentand grading procedures designed to permit only a few students to succeed (those at the top of therank-order distribution) must now be revised to permit the possibility that all students could succeedat some appropriate level.Furthermore,procedures that pennitted (perhaps even encouraged) somestudents to give up in hopelessness and to stop trying must now be replaced by others that promotehope and continuous effort.In short,the entire emotional environment surrounding the prospect ofbeing evaluated must change,especially for perennial low achievers. 　　The students' mission is no longer merely to beat other students in the achievement race,At least part of their goal must be to become competent.teachers must believe that all studentscan achieve a certain level of academic success,must bring all of their students to believe thISOf themselves,must “accommodate” the fact that students learn at different rates by making use of differentiated instruction,and must guide all students toward the attainment of standards. 　　The driving dynamic force for students cannot merely be competition for an artificialscarcity of success.Because all students can and must succeed in meeting standards,cooperationand collaboration must come into play.The driving forces must be confidence,optimism,andpersistence-for all,not just for some.All students must come to believe that they can succeedat learning if they try.They must have continuous access to evidence of what they believe to be credible academic success,however small.This new understanding has spawned increased interestin formative assessment in recent years.

Which is meant by the author about the emotional promise of assessment for students?

A. To reach a minimum level of achievement.
B. To build up their co血dence in success.
C. To enable them to compete with others.
D. To help them realize their goals.