Topic: Degree of Comparison,

Best Answer Explained in Below-:

The sentence 'Helal's luck could not have been - than Ahnaf.' requires a comparative adjective to make a comparison between Helal's luck and Ahnaf's luck. In English grammar, 'worse' is the comparative form of the adjective 'bad,' specifically used when comparing two things.

Option A, 'worse,' is the correct choice because it effectively communicates that Helal's luck is not as poor as Ahnaf's. The comparative form is necessary here to establish the comparison, which the sentence structure implies.

Option B, 'worser,' is incorrect because it is a non-standard form and not accepted in English.

Option C, 'worst,' is a superlative form that is used when comparing three or more items, which does not fit the context here.

Option D, 'worsen,' is a verb that indicates the action of becoming worse, making it unsuitable for this sentence structure.

Therefore, 'worse' is the only option that correctly fulfills the requirement of a comparative adjective to compare luck between Helal and Ahnaf.