To determine the equation of the periodic function based on the provided table, we can analyze the values of \( y \) corresponding to the values of \( x \):
- At \( x = 0 \), \( y = 0 \).
- At \( x = \frac{\pi}{2} \), \( y = \frac{3}{4} \).
- At \( x = \pi \), \( y = 0 \).
- At \( x = \frac{3\pi}{2} \), \( y = -\frac{3}{4} \).
- At \( x = 2\pi \), \( y = 0 \).
From these observations, we can recognize the following points:
- The function starts at \( (0, 0) \), rises to \( \frac{3}{4} \) at \( x = \frac{\pi}{2} \), returns to 0 at \( x = \pi \), drops to \( -\frac{3}{4} \) at \( x = \frac{3\pi}{2} \), and returns to 0 at \( x = 2\pi \).
Thus, the function displays a characteristic sinusoidal behavior, which strongly resembles the sine function transposed and scaled.
To determine the correct equation, we note the following:
- The maximum value at its peak \( y = \frac{3}{4} \) suggests amplitude of \( \frac{3}{4} \).
- The sine function \( \sin(x) \) has a value of 0 at \( x = 0 \) and \( x = \pi \), and reaches its minimum at \( x = \frac{3\pi}{2} \).
- The output is positive for \( x = \frac{\pi}{2} \) and negative for \( x = \frac{3\pi}{2} \), which matches the behavior of a negative sine function.
Considering all these factors, the function that fits these values is most appropriately given by the equation:
\[ y = -\frac{3}{4} \sin x \]
So the correct answer is:
B. \( y = -\frac{3}{4} \sin x \).