(C) Assertion (A) is true, but Reason (R) is false.
Xylem transports water and minerals from roots to all parts of the plant; it is present throughout the plant — roots, stem, and leaves — not only in roots.
The Assertion is correct (xylem = water + mineral transport). The Reason is false because xylem forms a continuous vascular network through roots, stem, and leaves. Since A is true but R is false, option (C) is correct. Examiners expect you to evaluate both statements independently before choosing.