This strengthens by showing that it is possible for a virus to carry new DNA into reproductive cells. Remember, one part of Steele’s proposed hypothesis is that “a virus could carry the altered DNA to the reproductive cells and replace the DNA in those cells.”. But we don’t know whether this process can actually occur. (A) provides evidence that it can occur.

We already know that there’s a pattern of genes that Steele believes shows evidence that altered DNA has been transferred into reproductive cells. What matters is whether Steele is right in thinking that this shows altered DNA has been transferred into reproductive cells. Learning that we see the same pattern elsewhere doesn’t provide any evidence that Steele’s theory is correct. We still don’t know whether the pattern indicates what Steele thinks it indicates.

What matters is how mutations can be transferred to offspring. How the immune system tests out mutations against new diseases doesn’t matter, because we already know mutations occur and that mutations can help defend against new diseases. We have no reason to think the process of random trial and error described in (C) provides evidence that Steele’s view of how mutations are passed to offspring is correct or plausible.

This doesn’t strengthen Steele’s position, because we don’t know whether the giraffes’ evolution of longer and longer necks involves acquired characteristics being passed to offspring. Perhaps the giraffes evolved longer necks because the ones with longer necks were more likely to survive and have offspring.

(E) involves passing along characteristics through yolk sacs to chicks that are already conceived. It’s not clear how this relates to Steele’s hypothesis, which involves passing along acquired traits through DNA in reproductive cells. Steele isn’t proposing a method by which acquired characteristics are passed along to a gestating fetus.