Final answer:
Internal auditors should exercise due professional care by being diligent, using their professional judgment, and staying updated with industry standards.
Step-by-step explanation:
When conducting an assurance engagement, internal auditors should exercise due professional care by taking necessary precautions and being diligent in their work. This includes performing thorough research, analyzing relevant data, and using their professional judgment to ensure accuracy and reliability of their findings. Internal auditors should also stay updated with the latest industry standards and regulations to guide their work.