Meirke turns on the water full blast to fill the bathtub with water.
Expect an increasing slope here.
Then turns off the water when he hears his phone ring.
Expect a zero slope (flat curve) here since he turned off the tap.
He goes and answers the quick phone call and returns to the bathroom and turns on the water again.
Again, expect an increasing slope here.
He once again gets distracted and goes off to text with his friends for a while, remembering to turn off the water to prevent a water disaster.
Again, expect a zero slope (flat curve) here since he turned off the tap.
He then comes back to the bathtub and the water is now all cold. He decides to pull the plug which slowly drains all the water out of the tub.
Expect a decreasing slope (less steep) here.
The 1st and 3rd graph is straight away incorrect since they match up the above situation.
The 2nd and 4th graphs match with the above situation.
The 4th graph shows a steeper slope meaning that water drains very fast so it is also incorrect.
Only the 2nd graph is correct since it exactly follows the situation.
1. increasing slope
2. zero slope (flat curve)
3. increasing slope
4. zero slope (flat curve)
5. decreasing slope (less steep, slowly drains)
Therefore, the 2nd graph best describes this situation of water level in the tub.