Analyze the difference between primary and secondary active transport mechanisms.

• A. Both primary and secondary active transport use ATP directly to move molecules against their gradient.
• B. Secondary active transport uses ATP directly, while primary active transport relies on a gradient created by secondary transport.
• C. Primary active transport uses ATP directly to move molecules against their gradient, while secondary active transport uses a gradient created by primary transport.
• D. Primary active transport moves molecules down their gradient, while secondary active transport moves molecules against their gradient.

Answer: (C)