Distance education is enrollment and study with an educational institution that provides lesson materials prepared in a sequential and logical order for study by students on their own. When each lesson is completed, the student mails or transmits the assigned work to the institution for correction, grading, comment, and subject matter guidance by qualified instructors. Corrected assignments are returned promptly to the student. This exchange provides a personalized student-teacher relationship. If a student slows his or her pace or fails to send assignments, the school provides encouragement. Although some institutions provide employment placement information and assistance, no reputable school ever guarantees a job to graduates.Distance education and self-study are different. Self-study materials provide no instructional service. Corrected assignments, examinations, and special help provided by a qualified facility are vital to a good learning situation. However, these are not part of self-study. There are many self-study courses and recordings available, and they may have value, but they clearly are not correspondence or distance education courses. Some institutions offer combination courses that provide training-in-residence for students who complete their distance education lessons. In-service or on-the-job training is required or provided with other courses and is a feature of many vocational distance education programs.Quality distance education institutions screen prospective students to assure that only those who can benefit from the courses are enrolled. While there are educational prerequisites for some academic subjects, interest and aptitude are the primary factors leading to success in most distance education courses. Because they provide alternative educational opportunities, distance education institutions try not to deny a prospective student the opportunity to succeed in a course- interest and experience are good indicators of future success.Distance education courses vary greatly in scope, level, and length. Some have few lessons and require only weeks to complete, while others have a hundred or more assignments requiring three or four years of conscientious study. Also, a wide variety of subjects is offered. Subjects include yacht design, accounting, medical transcription, nutrition, robotics, travel agent training, gun-repair, gem identification, computer programming, catering and cooking, and earning an entire high school diploma, just to name a few.There is an increasing recognition of "distance education" and many colleges offer credit for their distance learning courses or accept some distance education credits of resident students working toward a degree. In fact, many distance education institutions award their own academic degrees. Acceptance of students and awarding of academic credit is the prerogative of the receiving academic institution. Also, the employing organization may set its own credit acceptance policies. It is implied in the passage that students of distance education （）

A. enjoy greater freedom in choosing the subjects to study
B. do not have to meet any enrolling requirement at all
C. take longer to complete their study than college students
D. can usually enter college to work toward a degree