Which of the following statements is true about symports and antiports?

• A. Symports move molecules in opposite directions while antiports move them in the same direction.
• B. Both symports and antiports require energy to transport molecules.
• C. Antiports can only be part of active transport mechanisms, while symports can only be part of passive ones.
• D. If one molecule is moving into the cell via a symport, another molecule is also moving into the cell.

Answer: (D)