Hi waytowharton,

Another problem with those options is that they use less effective ways to communicate the intended meaning.

1. necessity for an occurrence of a technical or scientific breakthrough
2. necessity for a technical or scientific breakthrough occurring

Compare (1) and (2) with (3):

3. a technical or scientific breakthrough is necessary

This is a reasonably good way to take those options out, but necessity for is the bigger problem.
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Also, concede can take an object e.g. concede an election (which means yield the election) but concede the necessity is awkward. We need the rest of the sentence to understand what it means. If a clause is required after concede, then we should use the 'that clause'.
"... concede that A is necessary..."

Even if it were "... concede the necessity of an occurrence of a technical or scientific breakthrough ...", it is still too messy with necessity and occurrence.. Option (C) is simply "concede that A is necessary"

When they say wordy is not good, the point is that keep it as simple and straight forward as possible. SC uses formal, business English - clean, direct, straight forward. So avoid all unnecessary frills (as done in option (A)).
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Hello waytowharton,

We hope this finds you well.

To answer your query, as other experts have written, the only other demerit in Options D and E is that they are needlessly wordy and indirect, making them quite awkward.

We hope this helps.
All the best!
Experts' Global Team
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Hello expert,
Is there any grammatical error in B? If not, why rule out it?
The meaning in B is logical too and we don’t know the writer’s intended meaning cuz there is only one sentence and no context.
Need your opinions. Thanks

The meaning conveyed by the (B) version does not make sense.

Here's the complete (B) version.

Even their most ardent champions concede that nothing other than a technical or scientific breakthrough is needed before solar cells can meet the goal of providing one percent of the nation’s energy needs.

Notice the sentence is about what the "most ardent champions" concede. The "most ardent champions" are those who most strongly believe in the use of solar cells. So something that they "concede" would be a drawback or issue with the use of solar cells.

So, the sentence is not logical, because "nothing other than a technical or scientific breakthrough is needed" is something positive about the use of solar cells, not a drawback or issue with the use of solar cells.

Also, "nothing other than a technical or scientific breakthrough is needed before solar cells can meet the goal of providing one percent of the nation’s energy needs," isn't really logical.

It seems to convey that, before solar cells can meet the goal, nothing more is needed, as if perhaps, after solar cells can meet the goal, something other than a technical or scientific breakthrough will be needed.

So, "before" is not the right connector there. The use of "for" would make more sense, as in

nothing other than a technical or scientific breakthrough is needed for solar cells to meet the goal of providing one percent of the nation’s energy needs
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You could also think about this in terms of "necessary" vs "sufficient."

Choice (C) suggests that a technical or scientific breakthrough is necessary, but that doesn't mean that it's sufficient -- after all, even if we have the breakthrough, there's probably a lot that would need to happen before solar cells can meet the goal of providing one percent of the nation’s energy needs (i.e. mass manufacture/installation of solar cells, creation/demolition of infrastructure, passage of new laws/ordinances, construction approvals, etc., etc.).

Choice (B), on the other hand, suggests that NOTHING else is needed besides a technical or scientific breakthrough. In other words, (B) suggests that the breakthrough is in fact sufficient, and that doesn't really make sense. Does that mean that as soon as some scientist sitting in a lab has that breakthrough, we'll instantly reach the goal? Of course not. We'll need other stuff to happen before the breakthrough translates to actual changes in energy production.

So (C) makes a lot more sense.

I hope that helps a bit!
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