Classification (words – vowels): Three words contain exactly one vowel; one word contains two vowels. Identify the odd word.

Introduction / Context:
Word-classification often uses simple letter features. Here, each option is a three-letter English word. The criterion is the count of vowels (A, E, I, O, U). Three have exactly one vowel; one has two. The task is to pick the outlier with two vowels.

Given Data / Assumptions:

• DOG → vowels: O (1).
• DIN → vowels: I (1).
• FED → vowels: E (1).
• OUT → vowels: O, U (2).

Concept / Approach:
Count vowels in each word and compare. The unique case with two vowels is the odd one out.

Step-by-Step Solution:

Verification / Alternative check:
Check consonant count: the outlier has only one consonant (T), whereas the others have two consonants each.

Why Other Options Are Wrong:

Common Pitfalls:
Overcomplicating with alphabetic positions. The test here is a straightforward vowel count.

Final Answer:
OUT