Aptitude question on Calendar

Question

Which of the following day(s) can't be the 1st day of a century?
Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday. Justify your answer.

Answer 1

No. Of odd  days in first century is 5 so las day of this century will be friday...first day of next century is SATURDAY

Similarly no. Of odd days in first 2 centuries is 3 so last day is wednesday......first day of next day century is THURSDAY

For the first 3 centuries no of odd days is 1 so last day is monday.....first day of next century is TUESDAY

for first 4 centuries no of odd days is 0...so last day is sunday....first day of next century is MONDAY

 

same will repeat for every 4 centuries