The Point $P(4,2)$ Lies on the Curve $y=\sqrt{x}$ If Is the Point Q

The point $P(4,2)$ lies on the curve $y=\sqrt{x}$ . If is the point Q $(x, \sqrt{x})$ , use your calculator to find the slope of the secant line PQ (correct to six decimal places) for the value $x=3.89 .$

A) $-0.128743$
B) $-0.251743$
C) $0.461743$
D) $-0.391743$
E) $0.251743$