It was tricky - I have chosen "E" for the first time.
A, B, D are eliminated by obvious reasons.
We are left with C and E.
I remember the very similar question from MGMAT, where "double the figure" was preferred over "double what it was".
https://www.beatthegmat.com/twice-as-man ... 64683.html
So I remembered that "what it was" is worse, and voted for E.
Looking more closely at the options, now I see the difference:
C: twice what it was
in the 1970's.
(which is parallel to the
In the 1980's in the very beginning of the phrase).
E: two times greater than
the 1970's.
Here we mean that
the 1970's =
the 1970's rate, i.e. the rate of the year 1970.
This is not parallel, changes the meaning (single year 1970 instead of 1970's) and contains another error - the year can not be in a posessive form.
Sigh. Spent twenty seconds and got it wrong. Need to be more careful...
Can I ask, what is the source of the question?