13Plant Structure TransportEasy1 markWhich statement explains why transpiration occurs?ACarbon dioxide enters the leaf only when stomata are open, so water vapour diffuses out.BRoots constantly absorb water by active transport and this is eliminated by transpiration.CTranspiration occurs so the xylem can transport amino acids to the growing leaves.DWater produced during photosynthesis is excreted from leaves during transpiration.Grade answerGrading criteria