Adhesion in xylem refers to attraction between:
Correct option is B, Water and xylem wall. In WATER TRANSPORT problems like this, the accurate statement is Water and xylem wall; the others are common mix-ups. Not these: A) Water molecules only; C) Xylem elements; D) Solute molecules. 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.