Answer:
d. Actively transported into the phloem
Explanation: Source is the place where sugar are been produced and are active transported to actively growing part of plants that requires it. The actively growing plants part that requires sugar are called sink.
Photosynthate the end products of photosynthesis is what is been loaded into the phloem through active transport and then moved to sink i.e plant part that requires the sugar through a process called translocation. The sink in plant includes the fruits, leaves for some vegetables,flowers for ornamental crop,too or tuber, rhizomes.
When the phloem cell is damage there is reduction in transport of photosynthate or accumulation in a particular part of plant.
Actively growing parts of plant have a high demand for sugar or sucrose than the old and weak parts of plants.
