Statement A: The movement of substances through phloem is bidirectional.

Statement B: The source sink relationship is variable for transport of food through phloem is variable depending on the season.

During active photosynthesis the source of food for transport through phloem is leaf or green parts from where the food is transported to growing regions like shoot apex and storage regions like roots (downward direction) fruit and seeds. In the early spring when the new leaves are forming in the shoot apex, the food stored in the root is transported in upward direction