Observe the following incomplete letter sequence carefully. A specific pattern governs the order and repetition of the letters. Choose the option that best fills the blanks to complete the sequence logically and symmetrically.
x y _ z _ x _ z _ z x _ z z z

​Given: x y _ z _ x _ z _ z x _ z z z
Now, we check each options.
​Option (a): z z y x z
x y z z z / x y z x z / x z z z z
​Option (b): z z y z y
x y z z z / x y z z z / x y z z z
​(It is a logical repeating pattern.)​
​Option (c): z x z y x
x y z z x / x z z y z / x x z z z
​Option (d): z x z z z
x y z z x / x z z z z / x z z z z
So, the following pattern is: x y z z z
Thus, correct option is (b).