Which of the following could lead to a carrier facing penalties?

Ignoring safety regulations is critical because it directly impacts the safety of both passengers and crew. Regulatory bodies impose stringent safety standards for train operations to minimize risks such as accidents and injuries. If a carrier neglects these regulations, it can result in severe consequences including fines, legal action, and even the suspension of operating licenses. Adhering to safety protocols is not only a legal requirement but also essential for maintaining public trust and ensuring a safe travel environment.

While the other options may have operational implications or lead to administrative issues, they do not inherently threaten the immediate safety of individuals on board, making violations of safety regulations the most serious concern that can trigger penalties.