Bloggs,
In reference to your statement as follows, I take serious issue:
We contend that that should be either D or C, since the cost of providing D, C or E will be the same (or close enough to be insignificant).
Please do not include me in 'we.'
I would never contend that the difference is 'close enough to be insignificant!'
My position is that the difference (if any) would be
'vanishingly small.'