Odd One Out — In the triplets (14, 17, 23), (19, 22, 28), (17, 20, 26), (21, 23, 30), three follow +3 then +6. Identify the exception.

Introduction / Context:
Step-patterns in triplets are common: here, the dominant pattern is “add 3, then add 6.” We must locate the lone triplet that does not adhere.

Given Data / Assumptions:

• Triplets: (14, 17, 23), (19, 22, 28), (17, 20, 26), (21, 23, 30).
• We compare consecutive differences.

Concept / Approach:
Compute d1 = second − first and d2 = third − second for each triplet; compare against the target (+3, +6).

Step-by-Step Solution:
(14, 17, 23): +3, +6 ✓(19, 22, 28): +3, +6 ✓(17, 20, 26): +3, +6 ✓(21, 23, 30): +2, +7 ✗

Verification / Alternative check:
Any uniform alternative (e.g., +4, +6) fails at least two triplets. The +3, +6 profile fits three and isolates one.

Why Other Options Are Wrong:

• (14, 17, 23): matches +3, +6.
• (19, 22, 28): matches +3, +6.
• (17, 20, 26): matches +3, +6.

Common Pitfalls:
Summing first and second to get the third; that does not hold here and obscures the simple difference pattern.

Final Answer:
21, 23, 30