SISDIT
Hi all,
According to formal written English I have learnt so far, "decreased to almost 40%" means the
LEFTOVER is approximate to 40%, but definitely less than 40%.It is weird to say that
“decreased to almost 40%” means decreased to somewhere a little bit more than 40% only.So, probably there is a typo in the phrase of “decreased to almost 40%”. It is quite clear to replace "
to" by "
by". Then the phrase could be "decreased by almost 40%".
Accordingly, we will have 3 things:
1. Before = 80%
2. Amount of change = [something less than 40%]
3. After = 80% - [something less than 40%] =
[something greater than 40%], which properly fits the reasoning in option A.
Just my 2 cents

I saw you chose (A) in the above post, so I guess u changed your mind?...
By the way, just wanna confirm that
the latest update of the question is accurately cited from GMAT Club CAT. (I did take a screenshot). Therefore, there is no typo now. If any, maybe only author of the question knows...
Anw, regarding the "almost" topic, after careful consideration,
I think that the usage of "almost to" is justified IN THIS CASE.
The following is just my personal reasoning. I recommend that you consult experts/ native speakers for better clarification.
As we may know, "almost" is quite similar to "nearly". It means something/someone nearly reaches a particular point, but actually not, just somewhere a little bit lower/smaller than that point. For instance:
- It is almost 10pm now. (--> The meaning could be: It is 9:50pm now)
- We have sold almost 100 pictures. (--> We have sold 97 pictures)
- At the age of 20, she has travelled to almost 30 countries. (--> maybe she has been to 28 countries)
But let's think, in all the above examples that represent usual usage of "almost", this adverb is used from perspective of "positive progress" (don't mind, I just created this name). In other words, "positive progress" describes
something that starts at a lower point and finishes at a higher point.
- It comes without saying that a new day begin at 00:01am, then 00:02am,......., 8pm, 9pm, 10pm,...
- Right upon starting a business, we sold only 1, then 2 pictures... we continue to sell.. the number of pictures sold increased day by day
- The number of countries she has been to starts from 1, then 2,...., and finishes at 28 as of now.
But
context of the question is another situation in which we should stand at the higher point (80%) looking down to the lower point (40%). That is why "decreased to almost 40%" should have the meaning of [decreased to somewhere a little bit higher than 40%. e.g. 41%]. In the same fashion, "increased to almost 40%" would mean [increased to somewhere a little bit lower than 40% e.g. 39%]. That's it.
Having said that, I think your suggested change is cool. I could understand it.. without any doubt.
+kudos to you.