Select the most appropriate option that can substitute the highlighted segment in the given sentence. If no substitution is required, select ‘No substitution.’
If it had not rained, they would not postpone the programmes.

Correct option is C

The correct substitution of the highlighted part is "would not have postponed."
Explanation:
· The sentence is in the third conditional, which is used to express hypothetical situations in the past that did not happen.
· Grammatical Rule Used: The structure for third conditional sentences is:
· If + past perfect, subject + would/could/might + have + past participle.
· Corrected Sentence: If it had not rained, they would not have postponed the programmes.
Why other options are incorrect:
· (a) would be postponed: Incorrect because it is in the passive voice and does not fit the structure of the conditional sentence.
· (b) no substitution: Incorrect because the original sentence is grammatically incorrect.
· (d) would not postponed: Incorrect because "postponed" is missing the auxiliary verb have in the conditional structure.