The fact that a strain of yeast with a certain defective gene can use the human version of the gene to repair itself is evidence that yeast and humans - a) depend on the same food supply b) share a genetic code eliminate c) both have eukaryotic cells d) have identical genomes

Let's look at each individual
A) We know this is factually wrong; humans and yeast eat different things. This question is about the micro-level of molecules, so we cannot infer much about the food of the organisms.
B) This is correct. If we did not share a genetic code, the yeast cell would not have been able to "translate" the genetic information in human genes in order to fix the problem. The genetic code is universal in life as we know it; we can transfer microbial DNA in humans and our cell machinery will still be able to utilize it and this is the basis of DNA recombination.
C) Again, this is not necessary. See the example in B (there are prokaryotic bacteria that illustrate the point).
D) This is plain silly; the genome determines to an extreme part our appearance etc. and it is obvious that we only share a small part of our genome with yeast, and certainly not all of it!

The equator absorbs the most sunlight