Word-formation count: Using each letter only once, how many meaningful English words can be formed from the letters D, R, E, O?

Introduction / Context:
Given four letters D, R, E, O (one each), determine the number of common English words you can form, using each letter once. This checks methodical enumeration and knowledge of common anagrams.

Given Data / Assumptions:

• Letters: {D, R, E, O}.
• Use each letter once.
• Count standard, widely used English words.

Concept / Approach:
Well-known anagrams from these letters include DOER, REDO, and RODE. Each is an everyday word: “doer” (one who does), “redo” (do again), and “rode” (past tense of ride). All consume exactly the four given letters with no repetition. Other permutations like “ore d” or “oder” are either spaces/misspellings or foreign forms and do not count.

Step-by-Step Solution:
1) Check forms around root “do”: DOER, REDO.2) Check simple past pattern: RODE.3) Confirm no additional common words exist without repeating or dropping letters.

Verification / Alternative check:
Consulting common vocabulary lists shows all three are standard entries. The set is stable across learner’s and collegiate dictionaries.

Why Other Options Are Wrong:
“None/One/Two” understate the count; more than three would require accepting nonstandard or improper forms.

Common Pitfalls:
Including non-words or overlooking one of the three common anagrams. Work systematically to avoid misses.

Final Answer:
Three