Thanks for the question!
We're looking at a flaw - so this is an assumption family question and there must be a gap. Let's break down the argument: the conclusion is that tech. innovation rarely serves society's interest. Why? Because the innovators are motivated by greed.
(Note, I've taken some serious liberties in rephrasing things in that - "considerations of personal gain" is quite different than "greed", but often a dumbed-down version serves me better - as long as I remember that I dumbed-down the details, and may need to reconsider them later.)
What's the gap? It's pretty straightforward actually. Who says that if you're not motivated to achieve X, you can't achieve it? Perhaps greedy innovators end up inadvertently helping society. (D) states this in rather abstracted terms. In short, it states that the argument assumes that doing something won't achieve a goal if that wasn't the motivation.
Looking at the wrong answers:
(A) is an impossible answer - we don't evaluate premises!
(B) is the most tempting answer. The easiest way to see why it's incorrect is to notice the shift in focus. The argument is about whether a certain motivation (benefiting society) is required to achieve a certain end (benefiting society), not whether the project is viable. If the project were not commercially viable, the motivation might still be greed (or not), and if the project were commercially viable, it also has no bearing on whether the project benefits society.
My colleague came up with a good analogy for a more complex issue with (B):
Mike is rarely cool. Why? Because he cares about being honest. (B) would state
"the argument assumes that someone who is cool cannot be honest." A couple of issues: the argument is about whether someone
cares about being honest, not whether he or she
is honest. Plus, the argument concludes that Mike is
rarely cool - that leaves room for a cool person to care about honesty once or twice - (B) is too extreme.
(C) is tricky! But, in the end, we're not concerned with whether the innovation results in personal gain. It's whether innovation motivated by personal gain can result in something other than personal gain benefiting society.
(D) is correct, so don't mess with it.
(E) is strange-looking and out of scope! The "should" is a major warning. The argument is in no way about what people should or should not do.
I hope that clears it up.