I'd say a because it says it's magnetic field as decreased by 10% in the last century
The net force on the sled is 300 N
Explanation:
First of all, we start by finding the acceleration of the bobsled, by using the suvat equation:

where:
v = 6.0 m/s is the final velocity of the sled
u = 0 is the initial velocity
a is the acceleration
s = 4.5 m is the displacement of the sled
Solving for a, we find

Now we can find the net force on the sled by using Newton's second law:
F = ma
where
F is the net force
m = 75 kg is the mass of the sled
is the acceleration
Solving the equation, we find the net force:

Learn more about acceleration and Newton laws here:
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Answer: from vector law opposite we minus
Hence
425n-300n=125n to the right
Hints in left vector have -Ve sign while right have +Ve sign