To do a certain task X would take 3 times as long as Y and Z together; and Z would takes 4 times as long as Y and X together. Three of them together can complete the task in 10 days. How much time is taken by X and Z to complete the task?

A

$$18\frac{2}{9}$$ days

B

$$20\frac{1}{9}$$ days

C

$$21\frac{1}{9}$$ days

D

$$22\frac{2}{9}$$ days