Why must you never drive or operate an industrial lift truck across an incline?is question number five on the instructor's main set of questions. Please note you may or may not get this question on a forklift operator's training course. The actual answer expected is:
Industrial trucks are not designed to operate on side slopes and there is a strong possibility it will overturn.
Your wording does not have to be exactly as the answers shown above but should be capable of interpretation so as to mean the same as the answers above.