A well with -inside diameter 14 m is dug 10m deep. Earth taken out of it is evenly spread all around it to a width of 21m to form an embankment. The height (in meters) of that embankment is

A

$$\frac{3}{5}$$

B

$$\frac{3}{8}$$

C

$$\frac{2}{3}$$

D

$$\frac{3}{4}$$