Letter Pairs Relation
1. **Understanding the Problem:**
We are given a pattern of relationships between pairs of letters.
"CT" relates to "RQ" and "AI" relates to "DF".
We need to find a similar relationship for "SP" among the options: MD, DN, AD, AI.
2. **Analyze the First Pair: CT and RQ**
Let's look at the position of each letter in the alphabet (A=1, B=2, ..., Z=26):
C=3, T=20
R=18, Q=17
Compare positions:
From C to R: 3 to 18, difference = 18 - 3 = 15
From T to Q: 20 to 17, difference = 17 - 20 = -3
Check for a pattern:
Sum of positions of CT: 3 + 20 = 23
Sum of positions of RQ: 18 + 17 = 35
Difference in sums = 35 - 23 = 12
3. **Analyze the Second Pair: AI and DF**
A=1, I=9
D=4, F=6
From A to D: 1 to 4 = +3
From I to F: 9 to 6 = -3
Sum AI: 1 + 9 = 10
Sum DF: 4 + 6 = 10
4. **Observing the Pattern:**
For the first pair:
First letter increased by 15, second letter decreased by 3.
Sum difference: +12
For second pair:
First letter increased by 3, second letter decreased by 3.
Sum difference: 0
The difference in the first letter's increment between pairs is 15 and 3.
Second letter always decreased by 3.
5. **Check the Option that Matches the Pattern for SP:**
S=19, P=16
Apply same increments from second pair (as AI->DF is simpler):
First letter: 19 + 3 = 22 (V)
Second letter: 16 - 3 = 13 (M)
So SP would relate to VM if following the (AI->DF) pattern.
Since VM is not an option, try first pair increments:
First letter: 19 + 15 = 34 which exceeds 26, so wrap around: 34 - 26 = 8 (H)
Second letter: 16 - 3 = 13 (M)
So SP relates to HM. HM not in options.
Try sum preservation like AI->DF (sum = 10)
SP sum: 19 + 16 = 35
Check option sums:
MD: M=13, D=4, sum=17
DN: D=4, N=14, sum=18
AD: A=1, D=4, sum=5
AI: A=1, I=9, sum=10
No option sums equal 35.
6. **Look for Letter Position Offsets Between Each Pair:**
CT to RQ:
C (3) to R (18): +15
T (20) to Q (17): -3
AI to DF:
A (1) to D (4): +3
I (9) to F (6): -3
Notice that the second letter always shifts by -3.
For the first letter, shifts are +15 and +3 respectively.
It's possible the first letter shifts by multiples of 3, decreasing by 12 from first to second pair.
If we apply first letter shift as +3 (like AI->DF), second letter shift as -3 to SP:
S(19) + 3 = 22 (V)
P(16) - 3 = 13 (M)
VM is not an option.
If we apply first letter shift as +15 (like CT->RQ), second letter shift as -3:
S(19) + 15 = 34 - 26 = 8 (H)
P(16) - 3 = 13 (M)
HM not in options.
7. **Try the option that resembles AI (A I) and DF (D F) pattern:**
Option d) AI is already a pair from example, unlikely.
8. **Try to check option b) DN:**
D=4, N=14
If SP (19,16) relates to DN (4,14):
First letter shift: 4 - 19 = -15 -> consistent with negative of 15 earlier
Second letter shift: 14 - 16 = -2 (close to -3 from pattern)
9. **Conclusion:**
Given the options, DN (option b) has first letter shift as -15, matching first pair but negative direction, and second letter shift close to -3.
Thus, SP relates to DN by similar first letter shift magnitude and near second letter shift.
**Final answer:** b) DN