Three of the following four letter-cluster pairs are alike in a certain way and one is different. Select the odd one.

PORT : TROP MODE : EDOM LIMB : BMIL FIST : IFTS

FIST : IFTS

The logic followed here is Ist letter = reverse of ist letter PORT : TROP = TROP MODE : EDOM = EDOM LIMB : BMIL = BMIL FIST : IFTS ≠ TSIF