Well, the surface of still water has surface tension. If there isn't enough mass or weight to break the surface tension, the object will float.
Given :
A 120 kg box is on the verge of slipping down an inclined plane with an angle of inclination of 47º.
To Find :
The coefficient of static friction between the box and the plane.
Solution :
Vertical component of force :

Horizontal component of force(Normal reaction) :

Since, box is on the verge of slipping :

Therefore, the coefficient of static friction between the box and the plane is 1.07.
Hence, this is the required solution.
D)
Explanation:
Coz the position changes with time but the position change is not constant throughout time So, D) does not have constant velocity