Ans B.
As question says – holding period was reduced by one quarter each time. In 2004 – third revision.
In 1993 holding period – 360 days ( four quarters). One quarter – $\frac{1}{4} \times 360 = 90$.
[quarter – each of four equal or corresponding parts into which something is or can be divided.]
First Time = $360 – 90 = 270$ (reduced by one quarter)
Second Time = $270 – 90 = 180$
Third Time = $180– 90 = 90$