Option A
This is clearly a case of lifted sentence line to justify that the question is being answered. Nevertheless, it is not what's needed in this context.
Wrong

Option B
This is a clear case of priortized emphasis on the singularity of "cost" which in actual sense is functioning in a plural capacity. The use of "their" blends well because it's in its plural form and combines the two head words well.
Right

Option C
The sentence is too long to be aptly defined but its lacking in agreement with the tenses used here especially "its" which is a possessive singular word. Clearly doesn't apply here.
Wrong

Option D
The sentence has changed the timing of the event which means it has happened in the past. The event wasn't stated to have occurred because the words expressed are in their present state.
Wrong

Option E
This still fall within the grammatically incorrect category because the organs here are not in agreement.
Wrong