Semi-dwarf rice varieties possess mutation in gene encoding:
GA20ox (C) is correct here. This is core Gibberellins: once you know the definition or pathway step, GA20ox is the clear fit. The wrong ones are A) GA3ox; B) GA2ox; D) GID1. 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.