Ethylene receptors function as:
Pick B: Negative regulators. Thinking through Phytohormone ALL step by step rules out the lookalikes and leaves Negative regulators. Skip these: A) Positive regulators; C) Transcription factors; D) Ion channels. 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.