Word formation – From the letters O, N, D, E, how many meaningful English words can be formed using all four letters exactly once in each word?

Introduction / Context:
This item again tests anagram recognition under the constraint “use all letters exactly once.” The letter set is O, N, D, E. We must count how many 4-letter standard English words arise from all permutations of these four letters.

Given Data / Assumptions:

• Letters: {O, N, D, E}.
• All four letters must appear once in each word.
• Only standard dictionary words qualify.

Concept / Approach:
Consider common anagram pairs: “DONE” and “NODE” are both straightforward and widely used words. Many other permutations (e.g., “ONED,” “EDON,” etc.) are not accepted as standalone words in general-purpose dictionaries.

Step-by-Step Solution:
Enumerate plausible candidates: DONE, NODE; test less obvious forms like D O N E → reorderings “ONDE/EDON/NEOD,” which are not valid standalone words.Confirm “DONE” (past participle of do) and “NODE” (a point in a network/graph; anatomical swelling) are valid.Total valid anagrams using all four letters = 2.

Verification / Alternative check:
Standard dictionary entries confirm both words. “NODE” is especially frequent in mathematics, computing, and biology contexts.

Why Other Options Are Wrong:

• None/One: Under-count; they miss one of the two valid anagrams.
• Three: Over-count; no third standard 4-letter word emerges from these letters without repetition.

Common Pitfalls:
Counting partial-letter words (e.g., “one”) is disallowed because the instruction demands using all letters. Also avoid abbreviations or capitalized names.

Final Answer:
Two