What Is/are the Advantage(s) of the Calvin Cycle Being Composed $\Delta$

What is/are the advantage(s) of the Calvin cycle being composed of multiple steps?

A) Energy flow is broken down into numerous reversible conversions.
B) Reversible conversions with near-zero $\Delta$ G values conserve more energy.
C) It provides substrates for sugar, amino acid, and nucleotide biosynthesis.
D) All of the above.
E) None of the above.