The answer is B. High voltage winding.
The high voltage winding has more cross-sectional area than the low voltage winding because it needs to carry more current. The current in a winding is proportional to the voltage divided by the resistance. The resistance of a winding is proportional to its length and inversely proportional to its cross-sectional area. Therefore, the high voltage winding needs to have a larger cross-sectional area than the low voltage winding in order to carry the same current without overheating.
The primary winding is the winding that is connected to the power source. The secondary winding is the winding that is connected to the load. The voltage in the secondary winding is proportional to the voltage in the primary winding, and the current in the secondary winding is proportional to the current in the primary winding.
The transformer is a device that transfers electrical energy from one circuit to another without a change in frequency. It does this by using electromagnetic induction to create a magnetic field that induces a voltage in the secondary winding. The voltage in the secondary winding is proportional to the number of turns in the secondary winding divided by the number of turns in the primary winding.
The transformer is a very efficient device, and it can be used to step up or step down voltage. It is used in a variety of applications, including power distribution, power transmission, and electronics.