That was my first thought as well, but this is my understanding of it...

I believe it is BERT → BGBS because "BGBS" follows the "only if". And the "only if" introduces the necessary condition. And the necessary condition has the arrow pointing to it (goes second). So if they are doing the environmentally right thing it must make good business sense.

"BGBS" → "BERT" would imply that in order for it to make good business sense the business must be doing the environmentally right thing, which I don't believe is what the statement is saying.

In this case the "BGBS" is the superset and therefore goes second; whereas "BERT" is the subset and goes first. So if a business is doing the environmentally right thing (subset), it must make good business sense (superset).

I found question 1 on the last skill builder "it's always sunny in Philadelphia" had a good and clear explanation of this.

I could be totally wrong but that's how I have been thinking of it!!