English usage – sentence improvement: Choose the best replacement for the idiomatic expression 'hell bent at getting' so that the sentence reads naturally and grammatically.

Given sentence
'The workers are hell bent at getting what is due to them.'

Concept/Approach
The fixed idiom is 'hell-bent on + gerund/noun'. Prepositions 'at' or 'for' are nonstandard here; 'upon' is formal but less idiomatic than 'on' in contemporary usage.

Step-by-step correction
Replace 'at' → 'on': 'The workers are hell bent on getting what is due to them.'

Common pitfalls
Using 'for' after 'hell bent' is incorrect; 'upon' is grammatically acceptable but markedly formal and not the conventional collocation.

Final Answer
hell bent on getting