51. If the following sentences were to be included in the passage, which paragraph should they go to?One good example is that many teachers today are asking students to keep a learning portfolio, whichis a purposeful collection of student works at different points of time in the semester. This portfolioexhibits students’ effort, progress, and achievements in one or more areas of the course.
(A) Paragraph 2.
(B) Paragraph 3.
(C) Paragraph 4.
(D) Paragraph 5.