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.

EB : YV :: VT : PN :: RO : ?

The correct option is LI.

To solve this letter-cluster analogy, we analyze the numerical positions of the letters in the English alphabet (where A = 1, B = 2, C = 3, ..., Z = 26).

Pattern Rule:
Subtract 6 from the alphabetical position of each letter in the first cluster to obtain the corresponding letter in the second cluster. If the subtraction goes below 1, we cycle backwards from Z (26).

Step 1: Analyze the first pair (EB : YV)
Letter positions:
- E = 5
- B = 2

Applying the rule (-6):

$\text{For E:}5-6=-1\Rightarrow 26-1=25\text{(Y)}$

$\text{For B:}2-6=-4\Rightarrow 26-4=22\text{(V)}$

Thus, EB is related to YV.

Step 2: Verify the pattern with the second pair (VT : PN)
Letter positions:
- V = 22
- T = 20

Applying the rule (-6):

$\text{For V:}22-6=16\text{(P)}$

$\text{For T:}20-6=14\text{(N)}$

Thus, VT is related to PN.

Step 3: Apply the pattern to find the missing letter-cluster (RO : ?)
Letter positions:
- R = 18
- O = 15

Applying the rule (-6):

$\text{For R:}18-6=12\text{(L)}$

$\text{For O:}15-6=9\text{(I)}$

Combining the resulting letters gives LI.