Which of the following definitions best fits 'occupational disease'?

The definition of 'occupational disease' is best captured by the choice that highlights illnesses related to work activities. Occupational diseases are typically illnesses that arise due to exposure to harmful substances or conditions in the workplace over time. This can include ailments caused by chemical exposures, repetitive motion, and other job-related hazards.

The option that suggests illnesses unrelated to work activities does not define occupational disease accurately, as these diseases inherently stem from the working environment or job responsibilities. Understanding this definition is crucial for workers' compensation claims, as proving that an illness is an occupational disease can affect eligibility for benefits. This distinction ensures that workers diagnosed with conditions connected to their employment can appropriately seek compensation for their medical costs and time away from work.