Correct Answer: Tuesday

Solution : Given:
18 September 1998 is a Friday.

Let's calculate the total number of days from the 18th of September 1998 to the 15th of September 2009 –

Number of remaining days in 1998 = 12 + 31 + 30 + 31 = 104
Number of days from 1 January 1999 to 31 December 2008 = (10 × 365) + 3 = 3653 (3 leap years)
Number of days from 1 January 2009 to 15 September 2009 = 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 15 = 258
So, the total number of days from 18 September 1998 to 15 September 2009 = 104 + 3653 + 258 = 4015
Now, on dividing 4015 by 7, we get 573 as the quotient and 4 as the remainder.

Therefore, add 4 to Friday, Friday + 4 = Tuesday

So, the 15th of September 2009 will be Tuesday. Hence, the third option is correct.