I went for A. Wow! Tough One.

Lets break it down.

We can actually break the sentence into two.

Which is better?
Less Availabilty OR Decreased availablity.

Less availabilty means that it is not found in large quantities. But 'Low availability' would have been grammatically better and correct.
Decreased availabilty means that it was available in higher quantities in the past.

So we go for Decreased availability.

That leaves us with C,D,E


C. Because of decreased availability and increased demand in scientific research, platinum remains expensive, like gold.
D. Because of decreased availability and increased demand for scientific research, platinum remains expensive, like gold.
E. Because of decreased availability and greater demand in scientific research, platinum remains at a consistently high price, like that of gold.

Which is better?
'increased demand in' or 'increased demand for' or 'greater demand in'?

Increased demand for scientific research does not explicitly state that Platinum was in demand. It can also be understood as an increased demand for scientific research in general.

So we are left with C & E
'increased demand in' or 'greater demand in'?
Both clearly state that the research was for Platinum.

E is wordy when compared to C.
'consistently high price' can simply be substituted with 'expensive'.

So C is the correct answer.
_________________

Give [highlight]KUDOS [/highlight] if you like my post.

Always do things which make you feel ALIVE!!!

I fell for 'A'. This is quite tricky..But learnt something out of this question...THank you all!
_________________

Thanks,
VP

Increase and Decrease are used to express change over a period of time, the intent of Platinum less availability and greater demand indicate change over time
Use Greater or less only when comparison is required
that yields to choice C&D
Platinum remains expensive because of Decreased availability of Platinum IN Scientific Research" seems more reasonable than "Platinum remains expensive because of Increased Demand FOR Scientific research".
C is the right choice

Nice question .... what's the source?
_________________

GGG (Gym / GMAT / Girl) -- Be Serious

Its your duty to post OA afterwards; some one must be waiting for that...

The question I believe is from Verbal Review - 2nd Edition.

demand in - correct idiom and makes sense in the current context.

demand for - incorrectly refers to the research.

use of 'like' is correct over here - since direct comparison is done between platinum and gold.

Hence C is the correct answer choice.

I hope this helps. Thanks.

I got this wrong but i understand the correct option now.

A is out for using greater, which is used for comparison.

Between C and D.

"demand in scientific research" and "demand for scientific research"

The intent of the sentence is to say "the increased demand of platinum in scientific research" is making it expensive and not just the "increased demand for scientific research".

Hence C

B and E went away first because of parallelism errors - less/increase and decreased/greater

A seems redundant with "remains consistently" and also "for" should be "in"

Narrowed it down to C and D and went with C because it had "demand in" and not "demand for"

You can immediately eliminate A, B, and E, because the only correct form is "decreased availability and increased demand". The other choices aren't parallel or grammatically correct.

Between C and D, I chose D, but I do realize now that C is correct. I misread the sentence, thinking it was saying there's an increased demand for scientific research, but that doesn't make sense. C is the right answer.

Criteria for elimination:
1) Demand for scientific research here is incorrect. "Because...research" is modifying platinum, so we are talking about the demand of platinum "in" scientific research. Eliminate A, B and D
2) like that of gold is incorrect. Had the sentence read as "the price of platinum is high like that of gold" in that case "like that of gold" would have been correct. However here the sentence reads as "platinum (like gold) is expensive". Eliminate E.

Hence the answer is C.

C is the correct answer.
First of all, we need the words "increased" and "decreased" here instead of "less" and "greater". "less" is used for uncountable nouns and "greater" is used when comparing numbers.
Also, "for" is the wrong preposition here. We need "in". The sentence is talking about platinum and its decreased availability coupled with its increased demand IN scietific research, not for scientific research.