What constitutes the 'two-second rule' in practical road driving evaluation?

1. Choosing a stationary object beside the road (tree, signpost) when the preceding vehicle passes it, and ensuring your vehicle does not reach that object before counting 'one thousand and one, one thousand and two'
2. Looking in the rear-view mirror once every two hours
3. Pressing the brake pedal for only two seconds during emergency stops
4. Shifting gears in exactly two seconds