Answer: Smoking cigarettes
Explanation: The other options don't cause pollution to form in the air besides smoking, from the particles it creates causing harm and damage to your lungs and fill the air with smoke particles.
a) For the motion of car with uniform velocity we have , 
, where s is the displacement, u is the initial velocity, t is the time taken a is the acceleration.
In this case s = 520 m, t = 223 seconds, a =0 
Substituting
The constant velocity of car a = 2.33 m/s
b) We have 
s = 520 m, t = 223 seconds, u =0 m/s
Substituting
Now we have v = u+at, where v is the final velocity
Substituting
v = 0+0.0209*223 = 4.66 m/s
So final velocity of car b = 4.66 m/s
c) Acceleration = 0.0209
Normal Force = 54 N
acceleration = 1.2 m/s^2
For Normal Force:
According to the force diagram, we can come up with the equation (all up and down forces):
10 sin 30 + Normal Force - 58.8 = 0
Normal Force = 53.8 N = 54 N
For acceleration:
According to the force diagram, we can come up with the equation (all left and right forces):
10 cos 30 - 1.5 = (6.0) (Acceleration)
Acceleration = 1.19 m/s^2 = 1.2 m/s^2
