Final answer:
In order for the crate to remain stationary, the applied force must be equal to or less than the maximum force of static friction. The force of static friction can be calculated using the equation fs = μs * N, where fs is the force of static friction, μs is the coefficient of static friction, and N is the normal force exerted by the floor on the crate. The maximum force of static friction can be given by fs = μs * m * g.
Step-by-step explanation:
In order for the crate to remain stationary, the applied force must be equal to or less than the maximum force of static friction. The force of static friction can be calculated using the equation:
fs = μs * N,
where fs is the force of static friction, μs is the coefficient of static friction, and N is the normal force exerted by the floor on the crate.
Since the crate is on a horizontal surface, the normal force is equal to the weight of the crate, which is equal to its mass multiplied by the acceleration due to gravity:
N = m * g,
where m is the mass of the crate and g is the acceleration due to gravity.
So the maximum force of static friction can be given by:
fs = μs * m * g.
You didn't provide the values of μs, m, or g in your question, so it's not possible to determine the exact amount of force that must be applied. However, the correct answer will be either option a) 1200 N, option b) 800 N, or option c) 1200 N, depending on the specific values given in the problem.