Which of the following statements about diodes and triodes is correct?
a. adjusting the grid within a diode will have more of an effect than it will in the triode.
b. triodes have three electrodes, whereas diodes have only a grid and a cathode. c. diodes are often utilized as amplifiers, whereas triodes are often used as rectifiers.
d. diodes, which are often utilized as rectifiers, have two electrodes.

The right answer is D.

A diode is a so-called active component, which is part (like the transistor) of the family of semiconductors. By definition, a diode refers to an electronic component with two electrodes. It is a polarized component which therefore has two electrodes, an anode, and a cathode. The cathode (sometimes called K, for Kathode) is located by a locating ring (there may be several rings, in this case, the locating ring is the one closest to the edge of the diode).

i think the answer is c hope this