Why is the malate-aspartate shuttle considered efficient in electron transport compared to direct mitochondrial NADH production?

• A. It directly transfers electrons to complex II, increasing ATP yield.
• B. It uses FADH2 instead of NADH, which is more efficient.
• C. It bypasses complex III, enhancing electron transport efficiency.
• D. It allows NADH electrons to enter the matrix without energy cost, maintaining proton pumping efficiency.

Answer: (D)