Consider the following actions : 1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously. 2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive 3. Detection of the tit of smartphone which results in the rotation of display between portrait and landscape mode In how many of the above action is the function of accelerometer required?

An accelerometer measures the vibration or acceleration of motion of a structure. It converts physical acceleration from motion or gravity into a voltage output.

Here's how accelerometers are used in each scenario:

1. Car Crash Detection/Airbag Deployment: Accelerometers trigger airbags by detecting sudden shocks. In a crash, the accelerometer (crash sensor) sends a signal to the airbag control unit, which then inflates the airbag.

2. Laptop Free Fall Detection: Accelerometers can detect the free fall of a laptop. This triggers a signal to immediately turn off the hard drive to prevent data loss.

3. Smartphone Tilt Detection: Accelerometers are used in electronic devices like smartphones, tablets, and laptops to detect orientation relative to gravity. This allows the device to determine 'up' from 'down' and rotate the display accordingly.

Therefore, the function of the accelerometer is required in all three actions.

Hence, option (c) is the correct answer.