Actually there is a slight difference in pronunciation. One is apport-uh-til and the other is appor-til. The difference is the extra "t" in the plural version. It's easy to miss though.
i heard 'pourquoi porte-t-il un gateau'. Does this make sense? does it translate to ' why is he carrying a cake'? i know its not the correct answer but im wondering if it makes sense.
I hear the (normally silent) "ent" of the ils/elles conjugation. I wondered if I am hearing things: I'm not crazy! https://blogs.transparent.com/french/french-interrogatives-inversion/ "...There can be some changes to pronunciation with inversion... [We know we] don’t normally pronounce the ending of third person plural verbs (like (ils/elles) dorment or disent). However, in their inverted form these endings must be pronounced. Thus, if you are asking if a group of people are sleeping:dorment-ils? You would actually pronounce this dorment-Tils?" However the difference is very small.
Pourquoi apporte-t-il un gâteau? and Pourquoi apportent-ils un gâteau? sound identical to me. Can anyone hear a difference?
...And if they sound the same, then shouldn't the singular version be accepted as well?