Answers for the IRS Link and Learn tests or tests in the workbook to obtain certifications are available through the local IRS office through the local IRS Relationship Manager.
For obvious reasons, it is not provided on-line or in the test booklet.
If you are grading the paper tests and need the answer sheets, you should be able to obtain them from the source described above.
If you are a potential volunteer trying to find out the answers, please note that the test is open book, without strict time limits, and is designed to make you think about the situations enountered in a filling tax returns. The situations you encounter when doing taxes may be more complicated than those in the test. If you are unable, unwilling, or do not have the time to look up the answers to questions in the available training material and reference documents, but pass the exam by using the answer sheet, how confident and comfortable would you feel when working with a taxpayer? You may want to rethink your decision to volunteer and the time commitment required.