On what dates of May, 2001 did Thursday fall ?

2001 year = 2000 year (Leap year) + 1 year (Simple)
Multiple of 400 years i.e. 800, 1200, 1600, 2000 have 0 odd days.
So, total days from 01/01/2001 to 1/05/2001.

Total days = 31 January + 28 February + 31 March + 30 April + 1 May = 121 days
Odd days = 121 ÷ 7 = 2 odd days
Since May 1, 2001 is a Tuesday, the first Thursday of May will be May 3, 2001.
The next Thursdays:
First Thursday: May 3, 2001
Second Thursday: May 10, 2001
Third Thursday: May 17, 2001
Fourth Thursday: May 24, 2001
Fifth Thursday: May 31, 2001

So, the dates when Thursday fell in May 2001 are: May 3, 10, 17, 24, and 31.

Thus, the correct answer is (d).