Correct option is D
The 555 timer IC can operate in Astable, Monostable, and Bistable modes, so the answer is D: Astable, monostable and bistable.
Explanation:
Astable mode:
This mode functions as a free-running oscillator, continuously switching between high and low states, generating a square wave.
Monostable mode:
This mode acts as a one-shot pulse generator, producing a single pulse of a predetermined duration when triggered.
Bistable mode:
This mode functions like a flip-flop, maintaining a stable state until an external trigger changes it to the opposite state.
