In her presentation, the head of the Better Business Bureau emphasized that companies should think of the cost of conventions and other similar gatherings as not an expense, but as an investment in networking that will pay dividends.
The structure is Not X but Y and X and Y should be parallel.
A) as not an expense,but as
If I break it down,
not an expense
but as an Investment
If I remove but -> there are two "as" -> Incorrect
B) as not expense,but
We have an investment, we require an expense
C) not an expense,rather
Not X but Y is the structure
D) not as an expense,but as
E) not in terms of expense,but
We require in terms of Investment to make it parallel but we don't have that so incorrect