The last day of a century will not be?

100 years contain 5 odd days. (so, the last day of the 1st century is Friday.)
200 years contain (5 × 2) = 3 odd days. (so, the last day of the 2nd century is Wednesday.)
300 years contain (5 × 3) = 15 = 1 odd day(so, Last day of 3rd century is Monday.)
400 years contain 0 odd days. (Last day of the 4th century is Sunday.)
This cycle is repeated.
Therefore, the last day of a century cannot be Tuesday or Thursday, or Saturday.
Hence, option 4 is the correct answer.