Final answer:
The DC bias for a transistor amplifier should be in the active/linear region.
Step-by-step explanation:
In order for a transistor to operate as an amplifier, the DC bias (Q operating point) must be in the active/linear region.
When the transistor is biased in the active region, it is able to amplify small changes in the input signal. This region allows for a linear relationship between the input and output signals, which is desirable for amplifier applications.
For example, in an audio amplifier circuit, the sound waves from a microphone cause a diaphragm to move, which varies the input current to the transistor. The transistor amplifies this signal and drives a loudspeaker, resulting in an amplified sound.