The series represents dates, and the differences between consecutive dates are 18 days (Dec 4 to Jan 1), 28 days (Jan 1 to Jan 29), and 28 days (Jan 29 to Feb 26). The pattern of the difference changes. The dates are: 4th Dec 1995, 1st Jan 1996, 29th Jan 1996, 26th Feb 1996. The differences in days are: 31-4 = 27 days remaining in Dec + 1 day in Jan = 28 days. The number of days between 04/12/1995 and 01/01/1996 is 27 days (remaining in Dec) + 1 day (in Jan) = 28 days. The number of days between 01/01/1996 and 29/01/1996 is 28 days. The number of days between 29/01/1996 and 26/02/1996 is 28 days (Jan has 31 days, so 31-29=2 days left + 26 days in Feb = 28 days). Following this pattern, the next difference should also be 28 days. Adding 28 days to 26/02/1996 brings us to 25/03/1996 (Feb 1996 has 29 days as it's a leap year, so 29-26=3 days left in Feb + 25 days in March = 28 days).