Final answer:
The rungs of a ladder should be slip-resistant to minimize slipping.
Step-by-step explanation:
The subject of this question is Occupational Safety and Health Administration (OSHA). OSHA is a U.S. agency that sets and enforces safety standards in the workplace, including regulations for ladders.
The rungs or steps of a portable or fixed ladder should be slip-resistant to minimize slipping. This means that the ladder should have a surface that provides sufficient friction or grip to prevent slipping.
Options 1, 2, and 4 ('Smooth', 'Textured', and 'Grooved') are all related to the surface characteristics of the ladder rungs. Of these options, the correct answer is option 3: 'Slip-resistant'.