Q. Correct circuit to study input-output characteristics of an $n-p-n$ transistor in CE configuration is
Semiconductor Electronics: Materials Devices and Simple Circuits
Solution:
Observe that emitter $(E)$ is connected to both batteries, so it is common. Emitter $E-n$ side is connected to negative of $V_{B B}$ battery, collector $C-n$ side is connected to positive of $V_{C C}$ battery, active state.