Hi alltimeacheiver!

**Just a quick note - you probably want to re-post this in the DS forums (along with the earlier questions you posted) - I answered prior to realizing that they had been posted in the PS forum. I would suggest linking to this post in the DS forum**

Just like with any other DS problem, lets start with a rephrase of the question stem:

The product a(b-c) will equal 0 whenever a=0 or b-c=0 (the only way for a product to =0 is for 0 to be a factor). We can go one step further with the equation b-c=0; move c to the other side and we get b=c.

Therefore the rephrasing is this:
Does a=0 or does b=c?

Statement (1):
Let's simplify by grouping like terms (add "b" and "c" to both sides)
b-c = c-b
2b-c = c
2b = 2c
b=c
SUFFICIENT

Statement (2):
Again we start by simplifying - cross multiply:
b^2 = c^2
Because these are both positive (as stated in the problem), we can simply square root both sides and ignore the negative solutions:
b=c
SUFFICIENT

The correct answer is D

Hope this helps!

Whit