Final answer:
Without the mass of the refrigerator or information about opposing forces such as friction, we cannot determine the acceleration of the refrigerator when pushed with a force of 400 N. Newton's second law, a = Fnet / m, would be used if such information were available.
Step-by-step explanation:
The acceleration of the refrigerator can be found using Newton's second law of motion, which states that the acceleration of an object is the net force acting upon it divided by the mass of the object (a = Fnet / m). If a person begins pushing on a refrigerator with a force of 400 N, and we assume the only other force acting is friction (which isn't specified in the question), then we need to know the mass of the refrigerator to calculate the acceleration. However, since the exact mass of the refrigerator is not given, and we are not given any additional information like friction forces, we cannot calculate the acceleration directly.
For a hypothetical situation, if we had the mass, we could use the equation a = Fnet / m. Given that 'Fnet' would be the 400 N minus any opposing forces (like friction), and 'm' would be the mass of the refrigerator. Once Fnet is determined and divided by the mass, you would have the acceleration in meters per second squared (m/s²).
Being unable to solve the problem exactly due to insufficient information, none of the provided options (1) a = 2 m/s², 2) a = 400 N, 3) a = 0.5 m/s²) can be selected with confidence without additional information such as the refrigerator's mass or the net force after subtracting any opposing forces.