The correct answer is: B. Alternating current to Direct current.
A rectifier is an electrical device that converts alternating current (AC) to direct current (DC). This is done by using a semiconductor device, such as a diode, to allow current to flow in only one direction. Rectifiers are used in a variety of applications, including power supplies, battery chargers, and inverters.
Option A is incorrect because rectifiers do not convert DC to AC. Option C is incorrect because rectifiers do not convert high voltage to low voltage. Option D is incorrect because rectifiers do not convert low voltage to high voltage.