Explanation:

Correct Answer is (b).The original sentence is erroneous.
Reason: Usage of the phrasal verb 'cut off' which means ‘an act of stopping or interrupting the supply of something' is inappropriate in this sentence.
'Cut down' which means ‘reduced in scope or length’ would be suitable in this context.
E.g.: The doctor advised him to cut down his working hours.
Hence ‘cut down’ should be used in place of ‘cut off’ to make the sentence grammatically and contextually correct.
Among the given choices, only option B replaces the given bold part most appropriately.
The sentence after replacement becomes:
The rise in petrol prices did not lead to a proportionate cut down in consumption.Option B is hence the correct answer.