Chemistry planar question

Hi,please could i have help on this question? I thought the answer would be C since they all are arranged in a plane but it is D?
Here is the question: https://app.gemoo.com/share/image-annotation/584501237608202240?codeId=DW22qnAzdbplW&origin=imageurlgenerator

Thanks!

I would suggest making a model of each molecule (if you have a molecular modelling kit) or using MolView (a free website you can find with relative ease) to visualise what they look like in 3D. You should notice that C3H6 is not planar, as the hydrogens stick out and so the molecule can’t be thought of as flat (i.e planar).

I think it is D. One of the end carbons on C3H6 exhibits tetrahedral geometry due to it having 3 H atoms attached to it, which means there is more than one plane. Hopefully that helps?