The amplifiers do not work to their proper form when used in a circuit if
(A) Output is low
(B) Noisy
(C) Output and input changes
(D) Output is larger than input

Hint :Here we have been asked about the factor which will affect the working of an amplifier. For this, we will discuss the basic operation of an amplifier i.e. what we mean by an amplifier and what it is used for or what its purpose is. Lastly, we will discuss the factors which can affect the efficiency to arrive at our conclusion.

Complete Step By Step Answer:
First of all, what do we mean by an amplifier? An amplifier is an electronic device or circuit which is used to increase the magnitude of the signal applied to its input.
An amplifier amplifies every type of signal that is provided to it (under the working range of the amplifier) whether it contains information as well as some noise along with the information. The performance of an amplifier mainly depends on the type of input provided. If the input consists of some impurities or noise, then the output of the amplifier is affected as it also amplifies the noise along with the information signal.
If we think about it, Noise is just an unwanted signal that creates disturbance to the desired signal content in the system. Now where can this noise come from? Noise can be an additional signal that can be produced within the system or it can be some type of disturbance carried along with the input signal.
Therefore, out of all the options provided above, noise is the only factor that is affecting the output of the system and not letting the amplifier to work to its proper form when used in a circuit.
Hence, option (B) is the correct answer.

Note :
Noise can be produced within the circuit through the biasing current, input and output resistances, accuracy of the feedback resistance, etc. Whereas it can also come along with the input signal. For example: environmental sounds.