well i have contradicting replies so is it coz its a unreal situation while portion is singular
or portion is plural ??
Depends on how you want to look at it. SC problems can be solved in many ways. Usually they throw in at least two grammatical errors so if you can't spot one, try spotting the other.
In this case, we can take out D right away because 'was' is the wrong tense for plural 'portion of capital'
You can also take out B and A because there is not a requirement to use the present perfect tense 'have been'
That leaves us down to C and E. You can throw E out of the window because it uses the past perfect 'had been' when there is not a need for it (we're not trying to compare two past events).
Or if you prefer to have it another way, you can throw E out of the window because this is a unreal condition and we need the 'were' in C.