Under the 'Grammar point' in Lesson 1, point (i) states: 'We use -ing verb after various verbs connected with liking or not liking something: like, love, enjoy, hate'. 'Prefer' is not listed among these specific verbs.
Class 6 › English Grammar and Composition › Chapter 5: The -ing form of Verb: Gerund & Participle › Topic: The -ing form of verbs: Gerund
Aligned to the NCTB national curriculum.