Which of the following words is closest in meaning to 'foment'?

The word 'foment' means to instigate or stir up, particularly in the context of promoting a negative or troublesome situation, such as unrest or rebellion. Therefore, the word closest in meaning is 'to encourage,' as fomenting often involves encouraging certain actions or feelings, even if they are disruptive.

In this context, while 'to diminish' refers to reducing or lessening something, and 'to criticize' implies expressing disapproval, both diverge from the meaning of 'foment.' 'To fabricate' means to create or invent, often with a connotation of deceit, which also does not align with the essence of 'foment.' Thus, 'to encourage' accurately captures the essence of inciting or promoting something, aligning perfectly with the meaning of 'foment.'