I believe the answer is C
The final atmospheric pressure is 
Explanation:
Assuming that the temperature of the air does not change, we can use Boyle's law, which states that for a gas kept at constant temperature, the pressure of the gas is inversely proportional to its volume. In formula,

where
p is the gas pressure
V is the volume
The equation can also be rewritten as

where in our problem we have:
is the initial pressure (the atmospheric pressure at sea level)
is the initial volume
is the final pressure
is the final volume
Solving the equation for p2, we find the final pressure:

Learn more about ideal gases:
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Explanation:
It is given that,
Mass of person, m = 70 kg
Radius of merry go round, r = 2.9 m
The moment of inertia, 
Initial angular velocity of the platform, 
Part A,
Let
is the angular velocity when the person reaches the edge. We need to find it. It can be calculated using the conservation of angular momentum as :

Here, 


Solving the above equation, we get the value as :

Part B,
The initial rotational kinetic energy is given by :



The final rotational kinetic energy is given by :



Hence, this is the required solution.