More than 25 per cent of the 59,100 candidates who secured admission in Delhi University's first round of seat allocations have frozen their seats while nearly 60 per cent of them have opted for an upgrade to their higher 'programme+college combination' preference, a university official said Thursday.Thursday was the last day for opting for an upgrade. "As many as 35,388 students have opted for an upgrade, while 15,398 have frozen their seats," the official said. It was not immediately clear the status of the rest about 8,300 candidates. 'Freezing seat' means that a candidate has locked the 'programme+college combination' they got and they will not be looking for an upgrade.