P and Q are stationary points at the two ends of a string. A transverse stationary wave with a constant maximum amplitude is produced on the string. P, R and Q are the only positions on the string at which nodes occur. S and T are two points on the string, each at a distance $x$ from R. What is the relationship between points S and T?
- Athe same amplitude and in phase
- Bdifferent amplitudes and in phase
- Cthe same amplitude and a phase difference of $180^{\circ}$
- Ddifferent amplitudes and a phase difference of $180^{\circ}$