Answer:
D. 2 and 4 only (Phloem Sieve Tube and Xylem Vessel)
What is the mass flow?
The net movement of material matter from one location to another.
Examples of mass flow include blood circulation and transport of water in vascular plant tissues.
What is a xylem?
A compound tissue in vascular plants that helps provide support and that conducts water and nutrients upward from the roots, consisting of tracheid's, vessels, parenchyma cells, and woody fibers.
Therefore, xylem vessels carry fluids by mass flow as they conduct water while sending nutrients towards the roots of a vascular plant.
What is a phloem sieve tube and how does it have mass flow:
In vascular plants, sieve elements are elongated live cells of the phloem whose nuclei have fractured and vanished and whose transverse end walls are punctured by sievelike groups of holes (sieve plates). They transfer nourishment (mostly sugar) from the leaves to the remainder of the plant.