In the following triads, each group of letters is related to the subsequent…

Concept — In a letter-cluster analogy every later cluster is produced by a fixed position map applied to the letters of the first cluster. Number the letters of the first cluster 1-2-3-4 and describe each following cluster purely by the order in which it uses those numbered slots. The particular letters never matter; the position pattern is what has to repeat across the whole triad.

Application — Read both maps off the two sample triads.

1. TRUE is T = 1, R = 2, U = 3, E = 4. Its middle cluster RUTE spells R, U, T, E, which is the map 2-3-1-4: the first three letters shift one place left and the fourth letter keeps its slot.

2. Its final cluster EURT spells E, U, R, T, which is the map 4-3-2-1: the starting cluster written from its last letter back to its first.

3. WASH repeats both maps. Map 2-3-1-4 on W, A, S, H gives A, S, W, H = ASWH, and map 4-3-2-1 on the same letters gives H, S, A, W = HSAW.

4. So the logic to reproduce is fixed: middle cluster = map 2-3-1-4 of the starting cluster, final cluster = map 4-3-2-1 of the starting cluster.

Contrast — Apply both maps to each starting cluster on offer and set what the maps require beside the clusters actually given.

Cross-check — Both required clusters agree with the clusters actually given in exactly one row: LIFT yields IFLT under map 2-3-1-4 and TFIL under map 4-3-2-1. In every other row at least one cluster departs from the map — SAWN keeps S in front instead of leading with the second letter, URBC carries C to the end instead of writing CURB backwards, and APST and TASP are plain two-letter swaps of PAST rather than the required maps.

Answer — LIFT - IFLT - TFIL follows the same logic.