Critical Reasoning

Question Stem -
Unlike, wholesale price of lumber, the wholesale price of polymerized plastic has not fallen considerably in the last five years. Thus, although the retail price of wood-based products has not yet decreased, this will soon change, unless the trend in wholesale lumber prices is reversed.

Which of the following .....

I was trying to first analyze the question.

Here's my analysis:
The first sentence is straightforward.


Let's start with the second one: Thus, although the retail price of wood-based products has not yet decreased, this will soon change, unless the trend in wholesale lumber prices is reversed.


The retail price of wood-based products will decrease. (from the second sentence because "this will soon change" negates "not yet decreased". ....(i)
For the second part, "unless the trend in wholesale lumber prices is reversed" => the trend in wholesale lumber prices is not reversed. .......(ii)
Therefore , (i), if (ii) is the structure. Hence, The retail price of wood products will decrease, if the trend in wholesale lumber prices is not reversed. I understood this.

My question is : Do I need to reverse the "The retail price of wood products will decrease, if the trend in wholesale lumber prices is not reversed." Can anyone please help me?

Thanks
Voodoo