Can you provide a source for point D2? Admittedly, I don’t understand chemistry at all, but that seems strange to me, and I’d like to read more
This is not the article I read, but doing a quick "carbon 13 plant absorbing" search pulled this up as a top place: http://www.plantphysiol.org/content/plantphysiol/36/2/133.fu... Under controlled conditions, plants favor c12 to c13. But it's an old study(61) and there's been more recent work. Plus on different photosynthesis types. This paper doesn't seem to go through the different types. But yea, should give you a start.
I swear I'm looking for a paper done by Michigan State. But I can't find it. I'll update if I find it.