‘Whistleblowers are invaluable in exposing corruption.’ What does ‘invaluable’ mean in this context?

Directions: Read the passage carefully and answer the question that follows.

Corruption often goes unchallenged when people do not speak out about it. Witness accounts offer invaluable insights into corruption, and are powerful tools in the fight against it. From exposing multi-million dollar financial scams to dangerous medical practices, whistleblowers play a crucial role in saving resources and even lives.
But in some countries, blowing the whistle can carry high personal risk – particularly when there is little legal protection against dismissal, humiliation or even physical abuse. Controls on information, libel and defamation laws, and inadequate investigation of whistleblowers’ claims can all deter people from speaking out.
Whistleblowers are less likely to report workplace misconduct when their employers do not provide clear internal reporting channels. And in some settings, whistle-blowing carries connotations of betrayal rather than being seen as a benefit to the public. Ultimately, societies, institutions and citizens lose out when there is no one willing to cry foul in the face of corruption

Whistleblowers are invaluable in exposing corruption, fraud and mismanagement. Early disclosure of wrongdoing or the risk of wrongdoing can protect human rights, help to save lives and preserve the rule of law. When witnesses of corruption are confident about their ability to report it, corrupt individuals cannot hide behind the wall of silence.