An employee who mixes, loads, or applies pesticides with the signal word "DANGER" in the production of an agricultural commodity may work alone at night if the employee ___________.

The correct answer highlights the importance of ensuring safety while working with hazardous materials like pesticides marked with the signal word "DANGER." This label typically signifies a high level of toxicity, making it crucial for individuals working with these substances to have a support system in place, especially when working alone.

By requiring employees to make personal contact by radio with a responsible adult at least every hour, the regulation is reinforcing a protocol designed to enhance safety and enable prompt assistance if an emergency arises. This communication protocol ensures that someone is aware of the employee's situation, minimizing risk in case of an accident or health issue related to pesticide exposure.

This emphasis on regular check-ins is particularly important in contexts where individuals might be at increased risk due to isolation, as is the case when working at night. The other options fail to establish the same level of safety; for instance, having a cellular telephone does not guarantee regular communication or periodic check-ins, while the interval of contact in option B may not be frequent enough for safe practices in a potentially hazardous environment. Special training alone, while beneficial, does not substitute for the necessary communication and monitoring mechanisms required in these situations.