I think
egmat was correct in this case,
hazelnut, but the issue is more with the
placement of the phrase "at one time", and not really with the difference between "once" and "at one time."
I'm not sure if this little exercise will help, but let's see what happens if we swap "once" and "at one time", but keep the placement the same as before. So which of these two would you prefer?
(B)...many people who might at one time have died as children... now live well into old age.
(D) ... many people who in childhood might have at one time died... now live well into old age.
And what about now?
(B)...many people who might once have died as children... now live well into old age.
(D) ... many people who in childhood might have once died... now live well into old age.
And here's the actual answer choices again:
(B)...many people who might once have died as children... now live well into old age.
(D) ... many people who in childhood might have at one time died... now live well into old age.
The problem is that in (D), "at one time" seems to be modifying "died" -- and as Shraddha pointed out, that doesn't make a lot of sense. If we think about what that's saying strictly and literally, it seems to imply that the people died once in childhood, but then kept living -- or least that's what it seems to be saying. In (B), "once" modifies "might have" -- suggesting that it's possible in the past that they
could have died before modern medicine became more awesome.
It's a tricky question to explain! I'm surprised that it's tagged as sub-600 level -- this one is slippery, but I hope that this made some sense.
I have a confusion in choice B and choice E.
, placement of words is important here. I believe that the placement of word
should have been closer to the its reason i.e.
as X and Y.
Using this logic, I eliminated B as the word "died" is placed a little far from its reason.
).
I sense no error in the placement of "at one time" and believe that placement of "at one time" and "once" matters more than their individual meanings as both convey the same meaning if placed aptly.
E is wordy but that is not enough to eliminate it.
Please shed some light on this.