Those adults who read at the very lowest level get help (50) volunteer literacy

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Adult education is the practice of teaching and educating adults. This often happens in the workplace, through “extension” or “continuing education” courses at secondary schools, lifelong learning centers, at colleges or universities. Educating adults (46)______educating children in several ways. One of the most important differences is that adults have accumulated knowledge and experience that can add to or hinder the learning experience. Another difference is that most adult education is voluntary. (47)______, the participants are generally better motivated.
Adults frequently (48)______their practical knowledge to learn effectively. They must have a reasonable expectation that the knowledge recently gained will help them further their goals. Those adults (49)______ read at the very lowest level get help (50)______ volunteer literacy programs. These national organizations which provide training, tutor certification and accreditation for local volunteer programs.