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

COMFORT : FMOCTRO :: DIGNITY : NGIDYTI :: FOREIGN : ?

To find the missing letter-cluster, let us analyze the pattern of relationship between the first and second letter-clusters, as well as the third and fourth letter-clusters.

First pair: COMFORT : FMOCTRO
Let us write down the positions of the letters in COMFORT (numbered 1 to 7 from left to right):
1: C
2: O
3: M
4: F
5: O
6: R
7: T

Now let us look at the rearranged word FMOCTRO:
F (position 4)
M (position 3)
O (position 2)
C (position 1)
T (position 7)
R (position 6)
O (position 5)

This shows that:
- The first four letters "COMF" (1-2-3-4) are reversed to become "FMOC" (4-3-2-1).
- The last three letters "ORT" (5-6-7) are reversed to become "TRO" (7-6-5).

Second pair: DIGNITY : NGIDYTI
Let us verify this pattern with the second pair DIGNITY : NGIDYTI (positions 1 to 7):
1: D, 2: I, 3: G, 4: N, 5: I, 6: T, 7: Y

Reversing the first four letters "DIGN" (1-2-3-4) gives "NGID" (4-3-2-1).
Reversing the last three letters "ITY" (5-6-7) gives "YTI" (7-6-5).
Combining them gives "NGIDYTI", which matches the second cluster exactly.

Applying the pattern to FOREIGN:
Let us apply the same rearrangement logic to FOREIGN:
1: F
2: O
3: R
4: E
5: I
6: G
7: N

- Reversing the first four letters "FORE" (1-2-3-4) gives "EROF" (4-3-2-1).
- Reversing the last three letters "IGN" (5-6-7) gives "NGI" (7-6-5).

Combining these two parts, we get: EROFNGI.

Therefore, the related letter-cluster is EROFNGI.