Which part of plant has most negative water potential?
That points to D: Atmosphere. Compared with the other options, Atmosphere is the one that correctly describes the WATER POTENTIAL concept. The wrong ones are A) Root; B) Stem; C) Leaf. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.