This answer is to that one.

  1. preferable than
  2. more preferable
  3. most preferable
  4. preferable
Answer

D) preferable

"Preferable" already means "more desirable" – use "preferable to". Adjectives, Adverbs & Comparison · Degrees of comparison

English MCQ · More English: Adjectives, Adverbs & Comparison MCQs · Practise