The sentence to complete is: "Some people ___ themselves into believing that they are indispensable to the organisation they work for." To determine the best word to fill the blank, we consider the meanings of the given options:
- force: to make someone do something against their will;
- denigrate: to criticize unfairly or demean;
- delude: to mislead the mind or judgment of; deceive;
- fool: to trick or deceive someone into doing something.
The context of the sentence suggests that the individuals are misleading themselves into thinking they cannot be replaced by their organization. Therefore, the word that best completes the sentence is
delude, which means to deceive. So, the correct answer is: "Some people
delude themselves into believing that they are indispensable to the organisation they work for."