The situation appeared to be going from bad to ____ .
a. worst
b. the worst
c. worse
d. the worse

What's the correct answer?(EXPLAIN pls)
bad worse worst

so from bad to worse Emotion: stick out tongue
I think c. worse is the correct answer. The reason is because from bad to worse is an idiom.
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e.g. The weather is going from bad to worse.
 whl626's reply was promoted to an answer.