If 24 July 1999 was Saturday, then what was the day of the week on 28 July 2003?

Given:
24 July 1999 was Saturday

Number of days between 24 July 1999 and 28 July 2003 = 1465 days
On dividing 1465 by 7, we get 2 as remainder.

Saturday + 2 → Monday​
Therefore, 28 July 2003 Monday. ​​

Thus, the correct option is (a).