What is the primary difference between primary active transport and secondary active transport?

• A. Primary active transport requires no energy input, while secondary active transport requires ATP hydrolysis.
• B. Primary active transport is directly driven by ATP hydrolysis, while secondary active transport is driven by an electrochemical ion gradient.
• C. Primary active transport moves molecules with their concentration gradient, while secondary active transport moves molecules against their concentration gradient.
• D. Primary active transport occurs only in prokaryotic cells, while secondary active transport occurs only in eukaryotic cells.

Answer: (B)