Two small insects, which are x metres apart, take u minutes to pass each other when they are flying towards each other, and v minutes to meet each other when they are flying in the same direction. Then, the ratio of the speed of the slower insect to that of the faster insect is

A

$$\frac{u}{v}$$

B

$$\frac{u}{v - u}$$

C

$$\frac{v - u}{v + u}$$

D

$$\frac{u}{v + u}$$