Bleeding after a tonsillectomy is split neatly by timing. Anything in the first day is the early group, called primary or reactionary, and it is tied to a loosened tie or vessels that reopen as the patient warms up and blood pressure normalises. The late group is the secondary bleed.
The secondary bleed has a signature window of roughly the fifth to tenth day, with the sixth day being the textbook peak. The reason is biological: the protective slough that forms over the raw tonsillar bed separates around this time, and if infection has set in it can eat into an underlying vessel and trigger oozing or frank bleeding.
Scanning the options against this logic, both the hour based choices belong to the early reactionary category, and twelve days sits beyond the usual late window. The choice that lands inside the classic secondary interval is six days.
\[\boxed{\text{6 days}}\]