Root pressure is generated due to:
Correct option is B, Active accumulation of mineral ions in xylem. In WATER TRANSPORT problems like this, the accurate statement is Active accumulation of mineral ions in xylem; the others are common mix-ups. Not these: A) Passive diffusion of ions; C) Evaporation from leaves; D) Capillary rise. Tissue transport questions usually turn on xylem vs phloem, living vs dead cells, or source vs sink.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.