In the following question, a letter series is given. Some of the letters of the series are missing. This missing letters are given in same order as one of the four/five alternatives below the series. Find out the correct alternative.

rtx__sx__z__txy __ __yz

A. yyrxs
B. yysxr
C. yyrsx
D. yyxrs

Answer: Option C


Pattern of the series as shown below

rtxy/sxyz/rtxy/s xyz => yyrsx

Hence, the missing letters are yyrsx.