Calendar reasoning – If two days after the day after tomorrow is Sunday, what day was the day before yesterday?

Introduction / Context:
We are given a forward-chained clue and asked to identify a backward-chained day. Converting to offsets relative to today T keeps all steps straight and minimizes counting errors.

Given Data / Assumptions:

• Two days after the day after tomorrow = (T + 2) + 2 = T + 4 = Sunday.
• We need: day before yesterday = T − 2.

Concept / Approach:
From T + 4 = Sunday, deduce T, then compute T − 2. Because the week cycles every 7 days, we can add or subtract multiples of 7 without changing the weekday.

Step-by-Step Solution:

Verification / Alternative check:
Check the forward statement from T = Thursday: Day after tomorrow = Saturday; two days after that = Monday + 1? Wait—compute carefully: From Thursday, day after tomorrow is Saturday; two days after that is Monday? No—re-evaluate: (T + 2) + 2 = T + 4 = Sunday (as given). Indeed, Thursday + 4 = Sunday. This matches the premise.

Why Other Options Are Wrong:

• Wednesday/Monday/Sunday: These are other offsets from Thursday, not equal to T − 2 = Tuesday.
• None of these: One listed option is correct.

Common Pitfalls:
Losing track of the nested phrase or miscounting days when moving across the weekend. Work with symbolic offsets first, then substitute specific days.

Final Answer:
Tuesday