A straight line through the vertex P of a triangle PQR intersects the side QR at the point S and the circumcircle of the triangle PQR at the point T. If S is not the centre of the circumcircle, then

A

$$\frac{1}{PS} + \frac{1}{ST} < \frac{2}{\sqrt{QS+SR}}$$

B

$$\frac{1}{PS} + \frac{1}{ST} > \frac{2}{\sqrt{QS+SR}}$$

C

$$\frac{1}{PS} + \frac{1}{ST} < \frac{4}{QR}$$

D

$$\frac{1}{PS} + \frac{1}{ST} > \frac{4}{QR}$$