AND gate
A. It has no equivalence to switching circuit
B. It is equivalent to series switching circuit
C. It is equivalent to parallel switching circuit
D. It is a mixture of series and parallel switching circuit

Hint: AND gate is one of the types of logic gate which is used to carry out certain logical functions based on Boolean functions. These logic gates are used in digital systems as electronic circuits which are used to perform specific functions depending on the input signals.

Complete step by step solution:
An AND gate is a two input logic gate, in which if all the input signals are applied in the state of 1, then it gives a very high output that also has a value 1. It is formed by combining Resistor-Transistor switches. On the other hand, if all the inputs applied to the AND gate are not equal to 1, then the resulting output will not be high but low. It works according to the truth table to the right with Boolean expression,
Y=A.B
Therefore, in order to obtain an AND gate, both the inputs should be high and the switches should be in a closed position. This is possible only if the circuit is connected as a series switching circuit.

Therefore, option B is the correct answer.

Note: It is important to note that there are a total seven types of logic gates which include AND, OR, XOR, NOR, NAND, XNOR and NOT. These logic gates can have one or multiple binary inputs, but all of them will result in a single output. Depending upon the combination of resistors, transistors or diodes in a gate, these can be used in some electronic devices such as smartphones, tablets, micro processors, telephones.