Correct Answer: YWZZ

Solution : Given:
Z_XW_ZYXXW_YYXW_

To fill the series we have to divide the series – Z_XW / _ZYX / XW_Y / YXW_
Let's check each option –
First option: ZYWZ; Z Z XW / Y ZYX / XW W Y / YXW Z (No repeated pattern has been found. )
Second option: YWZZ; Z Y XW / W ZYX / XW Z Y / YXW Z (At each step, the fourth letter shifts to the first position followed by the first letter at the second position, the second letter at the third position, and the third letter at the fourth position.)
Third option: ZZYY; Z Z XW / Z ZYX / XW Y Y / YXW Y (No repeated pattern has been found.)
Fourth option: WYZY; Z W XW / Y ZYX / XW Z Y / YXW Y (No repeated pattern has been found.)

So, the series becomes ZYXWWZYXXWZYYXWZ. Hence, the second option is correct.