@dragon:

"Are you trying to suggest that an object would have to be there in order to see that we live in a 3D space? Obviously. We can see and feel that there is a length, width, and a depth to any object."

Of course "obviously", Dandan...

"4D space-time is a lot trickier, though"

Put aside time t temporarily for simplicity, please. Dandan...

@ benit:

"If you're talking about the concept of 3D space, it was probably known by anyone with eyes, but hard to describe mathematically until Euclid came around."

Yes.

@ studiot:

"Most life on Earth has stereoscopic vision, way back to the early days of evolution. So by the time Man came along creatures were working naturally in 3D.

I don't find it suprising that Man has developed more sophisticated understanding of dimensions than even those creatures with better stereoscopic vision than our own, just as he has in most (if not all) other areas of thought."

Yes. But put aside higher dimensions for simplicity, please. It's not the topic here.

@ Woody:

"As Studiot pointed out certain things are possible in higher dimensions, that are not possible with a smaller number of dimension.

The degrees of freedom of a system depends on its dimensionality

One can suspect that the appropriate balance between too few and too many degrees of freedom

for a sensible universe, might be the 3 plus 1 we observe."

Yes. But put aside higher dimensions for simplicity, please. It's not the topic here.

...............................................

So, the answer for the OP is "C"?