"Qu'est-ce que c'est" versus "Qu'est-ce que"

Question

I keep getting marked incorrect in my A0 quiz when asked to fill in the blank. Every time I will use one of these and it will say I should use the opposite. I don't understand why/when to use one variant over the other, especially when there is no indication of formality in the question. At this point I feel like I'm taking the quiz over and over due to this one mistake and just switching between the two but always incorrect.

Take "le Sacré Coeur" as an example, which variant should I use and why?

Qu'est-ce que c'est le Sacré Coeur?
Qu'est-ce que le Sacré Coeur?

Céline Pickard · Accepted Answer

Bonjour Shay,
This grammar point can be tricky. Both sentences ("Qu'est-ce que c'est le Sacré Cœur ? / Qu'est-ce que le Sacré Cœur ?") are correct and can be used interchangeably. You could also say : "C'est quoi le Sacré Cœur ?"

Attention:
- "Quoi est le Sacré Cœur ?" might look correct but it is not. 
- when using "Qu'est-ce que (c'est) + [...] ?", do not forget the -ce after "est"!
- Do not confuse:

Qu'est-ce que (c'est) / C'est quoi ? = What is it?

with
Qu'est-ce que (c'est que) ça/cela ? / C'est quoi ça/cela ? = What is this?

I also looked at your test hsitory and one of your answers (the one about Le Louvre) has now been amended as correct thanks to your comment as you used the correct expression. So it should show as such in that specific results board.
I hope this is helpful.