Select the option that is related to the fifth term in the same way as the second term is related to the first term and the fourth term is related to the third term.

TREE : RTEE :: KEEP : EKPE :: SOLO : ?

OSOL

The pattern seems to involve rearranging the letters of the original word.

1) TREE is rearranged to form RTEE.

2) KEEP should be rearranged to form EKPE.

Applying the same pattern to SOLO:

=> SOLO rearranged is OLOS.