Sodium and potassium ions are essential for muscle contractions of the heart. the ions are transported using a pump, which obtains energy by the breaking of . this action requires the expense of energy. so, sodium and potassium ions are transported using .

Answer is: active transport.
In active transport because energy is required to move the sodium and potassium ions against the concentration gradient. There is two type of active transport:
1) Primary active transport directly uses metabolic energy (adenosine triphosphate- ATP) to transport molecules across a membrane.
2) In secondary active transport (coupled transport) there is no direct coupling of ATP, energy derived from the pumping of protons across a cell membrane.

The answer is option a