I'm proofing something I've written and need to send before midnight.
I thought I was clear about the correct use of apostrophes but I'm not sure about wether an apostrophise is needed in the 'its' in the following sentence:
A cat's nap is often the highlight of its day.
I want to put it's because the nap belongs to 'it' but then it looks a bit like I'm incorrectly putting in an omission apostrophe for 'it is'.
Can anyone help please?