In this classic word riddle, what comes once in a year, twice in a week, and never in a day?

Introduction / Context:
This is a classic verbal reasoning riddle that tests attention to detail and lateral thinking rather than knowledge of calendar facts. At first glance, it appears to ask about special days in the year or unusual events. However, the real trick is that the riddle is about letters in words, not about months or festivals. Questions like this are very common in aptitude tests because they reveal whether the learner carefully examines the wording of the puzzle instead of relying on assumptions.

Given Data / Assumptions:

- The words given in the riddle are year, week, and day. - We are told that something appears once in the word year. - The same thing appears twice in the word week. - The same thing never appears in the word day. - The riddle does not explicitly say that the answer is a day or an event, so we must keep an open mind.

Concept / Approach:
The key idea is to stop thinking about calendar features and start thinking about the spelling of the words. If we scan the letters of year, we see Y, E, A, and R. If we scan the letters of week, we see W, E, E, and K. If we scan the letters of day, we see D, A, and Y. The puzzle is pointing to a letter that appears with different frequencies in these three words. Once we notice that the letter E appears exactly once in year, twice in week, and not at all in day, the riddle immediately makes sense and the confusing wording becomes clear and clever.

Step-by-Step Solution:
Step 1: Write down the three words: year, week, and day. Step 2: Look for a letter that appears once in year. Step 3: Check whether that same letter appears twice in week. Step 4: Confirm that the same letter does not appear at all in day. Step 5: Observe that the letter E appears once in year (Y, E, A, R). Step 6: Observe that the letter E appears twice in week (W, E, E, K). Step 7: Observe that the letter E does not appear in day (D, A, Y). Step 8: Conclude that the answer is the letter E.

Verification / Alternative check:
To verify, we can quickly test other possible letters such as A or Y. The letter A appears once in year and once in day, not matching the condition that it must never appear in day. The letter Y appears once in year and once in day and not at all in week, so that does not fit either. No other letter satisfies the pattern exactly. Only the letter E matches all three conditions simultaneously, so the riddle has a unique and consistent answer based on the spelling of the words given in the question.

Why Other Options Are Wrong:
Sunday and New moon day are tempting because they relate to time and special days, but they do not match the counts described in the puzzle. They occur many times in a year and not in the precise once or twice pattern mentioned. All of the above cannot be correct because Sunday and New moon day already fail to match the letter pattern. None of these is also incorrect because the letter E clearly satisfies the conditions once we analyze the spelling carefully.

Common Pitfalls:
A common mistake is to overthink the calendar aspect and search for rare festivals, leap years, or astronomical events. Another pitfall is to ignore the possibility that the riddle refers to letters instead of days. In competitive exams, puzzles often exploit this shift from meaning to spelling. Training yourself to check both the semantic level and the letter level is a useful habit. Carefully rereading the key words year, week, and day usually reveals the hidden pattern quickly.

Final Answer:
The thing that comes once in a year, twice in a week, and never in a day is the letter "E".