Crisis public relations refers to a series of self-rescue actions taken by companies to deal with crises, including eliminating impacts and restoring their image, due to poor corporate management, peer competition, and even malicious damage or external special events. According to the above definitions, Which of the following are crisis public relations:. ['Due to the typhoon, the outdoor billboard of a company was blown down by the wind, and the company sent employees to repair it.', 'Due to the theft of important production equipment of an enterprise, which seriously affected production, senior leaders held an emergency meeting to study countermeasures.', 'An enterprise loses its leading position in the industry competition, its profits have fallen sharply, and its senior leaders have decided to move to a new field.', 'After a chain store of a large restaurant group was exposed due to poor sanitation, the group leader apologized to the public through the media and took the opportunity to release new corporate hygiene management standards.']