The pressure-flow mechanism for sugar translocation you have learned about in this class is based on research on angiosperms, and thus might not occur in vascular plants. Which of the following real or hypothetical observations on gymnosperms would suggest they possess a different mechanism?

A.) Pores in the sieve areas of their sieve-tube members are filled with numerous membranes. 

B.) Gymnosperms do not possess vessels.

C.) Bidirectional phloem transport occurs in gymnosperms.

D.) Asymmetric annual growth rings occur in gymnosperms.

E.) Formation of buds is supported by products of photosynthesis primarily from leaves on the same branch.