Final answer:
The equation that describes the oscillation of the spring is y(t) = 4cos(2πt).
Step-by-step explanation:
The equation that describes the oscillation of the spring is y(t) = 4cos(2πt). This equation represents a cosine function because the description of the oscillation states that there is no horizontal or vertical displacement, which aligns with the cosine function. The amplitude of the motion is 4 inches, and the period is one second, which is why the equation includes 2π in the argument of the cosine function. Option A, y(t) = 4cos(2πt), is the correct equation to describe this function.