Through which of the following . Energy (ATP) is required to transport the ions and why ?
(a) Sodium - potassium pumps
(b) `Na^(+)` channels
(c ) `K^(+) ` channels

Explanation

To solve the question of which transport mechanism requires energy (ATP) to transport ions and why, we can analyze each option provided:

### Step-by-Step Solution:

1. **Understanding the Sodium-Potassium Pump (Option a)**:
- The sodium-potassium pump is a type of active transport mechanism.
- It moves sodium ions (Na⁺) out of the cell and potassium ions (K⁺) into the cell against their concentration gradients.
- Since this movement is against the concentration gradient (from lower to higher concentration), it requires energy in the form of ATP.
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