In plant systems, water potential is generally:
Negative (C) is correct here. This is core WATER POTENTIAL: once you know the definition or pathway step, Negative is the clear fit. The wrong ones are A) Positive; B) Zero; D) Infinite. If the topic is about gradients or potentials, water/solutes move from higher to lower of the relevant quantity.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.