Hey guys,
Thank you for the invitation to chime in! I'll throw my support for choice D here, as well. A few big-picture problems with some of the choices include:
-The use of "encouraged" in A and C - this "new scheme" doesn't call for a past-tense verb. At its most retroactive, you'd use the present perfect "has encouraged" to indicate that it's still ongoing, but a straight past-tense verb isn't correct here.
-"investments in meeting" or "investments for meeting" in choices A, B, and C are poorly phrased - that present-tense verb isn't really anything you can invest in, so in order to use a verb you really need to use the "to meet" infinitive form.
-"could" and "can" (E and B) aren't really good uses of business writing. As far as meaning goes, they're not something that a company like Knowledge Int'l would ever make an official statement on. "Will" and "Would" are better - they predict that something will happen instead of saying "maybe" or "it might". It's a subtle thing but I've seen the "nobody knows" forms of "can", "could", "maybe" come up and in contexts like these I haven't ever seen them be correct.
-Between D and E, E isn't really a pure parallelism error, as you could reverse the two verbs and it would be okay: "the program encourages older students and could support federal objectives". In that case, one thing is definitely true ("encourages") and the other is potentially true ("could support"), so the meaning is correct. But in the reverse order, as E is written, the conditional comes first making an awkward meaning "could support...and encourages" - the "could" really should control both verbs, and in this case that makes the second half illogical (you can't have "could" with an indicative form like "encourages").
I hope that helps...
One other point - I don't think that the GMAT would use "mature" vs. "older" in an official question as this question does...that seems to be a word-choice smokescreen that I haven't really seen them do. And 'investments" vs. "investment" - they're two different meanings but I think that both are appropriate here. "Investments" refers to specific levels or quantities of investments (e.g. "the government wants investments totaling $500 million"), whereas "investment" is the overall entity or idea. I don't think either is particularly wrong or right here.