Century starts — Which weekdays can a century year (…00) NOT start on?

Introduction / Context:Not all weekdays are possible for 1 January of a century year. Under Gregorian rules, century starts occur only on a subset of weekdays.

Given Data / Assumptions:

• Consider years …, 1700, 1800, 1900, 2000, 2100, …
• We examine which weekdays are attainable on 1 January of those years.

Concept / Approach:Empirical (and theoretical) analysis shows that century years start only on Monday, Wednesday, Friday, or Saturday.

Step-by-Step Solution:

Verification / Alternative check:Apply 100-year weekday shifts (+5, +6) and cycle through samples to see the attainable set.

Why Other Options Are Wrong:

• Options A–C include weekdays that actually can occur (e.g., Wednesday, Friday, Saturday). Hence none of those groupings are correct.

Common Pitfalls:

• Mistyping “Sunday” as “Sunady.”
• Assuming any weekday is possible.

Final Answer:None of these