Step 1: Understanding the Question:
This question tests knowledge of phloem transport in plants.
Step 2: Detailed Explanation:
The most abundant compound transported through sieve tubes is sucrose (D).
Sucrose is the primary transport sugar in most plants.
It is transported in the phloem sap along with other solutes.
Amino acids (A): Transported but not most abundant.
Organic acids (B): Transported in smaller amounts.
Proteins (C): Some proteins are transported, but not the major transported compound.
Thus, sucrose is the most abundant compound in phloem sap.
Step 3: Final Answer:
Thus, the most abundant compound transported through sieve tubes is sucrose, which corresponds to option (D).
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