Correct Answer: Thursday

Solution : Code for months –

Code for days –

Code for centuries –

For, 15 ^th of September, 2005 –
Formula: {Date + (Month code) + (Century code) + ( last two digit of the year) + ((last two digit of the year / 4)'s Quotient)} / 7

Date = 15
Code for the month (September) = 5
Code for the century (2000) = 6
(2005 = 2000 + 05; For 2000 it will be 6 and for 05 it will be 05)
And, 5 ÷ 4 = 1(Quotient)
Now, on adding them we get→15 + 5 + 6 + 05 + 1 = 32
On dividing 32 by 7, we get 4 as a remainder.
4 is the code for Thursday.

So, the 15 ^th of September 2005 will be Thursday. Hence, the second option is correct.