Class E genes act mainly as:
Pick C: Co-factors for ABC genes. Thinking through ABCE & ABCDE MODEL +Synapdrgon flowering step by step rules out the lookalikes and leaves Co-factors for ABC genes. Skip these: A) Structural proteins; B) Hormones; D) Enzymes. For hormones and genes, match the molecule or gene to its real role, not a neighboring pathway.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.