What must candidates do with scratch paper after the examination?

Candidates must return scratch paper to the supervisor after the examination to maintain the integrity and security of the test. This requirement is essential because any notes or calculations made on scratch paper may contain sensitive information or insights related to the exam questions. By collecting the scratch paper, the examination authorities can ensure that no materials that could compromise the testing process are taken away by candidates. This practice is common in standardized testing environments to uphold fairness and ensure that all candidates have an equal and secure testing experience. The other options either imply retaining potentially sensitive material or disposing of it improperly, which does not align with the protocols established for maintaining examination integrity.