Plant species differ in that renewed growth in spring can be triggered by day length or by temperature or else by a c...

Elizabeth on August 6, 2018

Why is the answer c?

I'm confused on why the answer is C? Could you explain it?

2 Replies

on August 31, 2018

Can you please explain why it is C

Max on September 1, 2018

@lizD the passage states that plant RG in spring can be triggered by DL, T, or both. So changes in when that trigger occurs year to year could be explained by DL, T or both. Since DL remains the same year to year, we know that the changes in when the trigger occurs year to year can't be fully explained by DL (otherwise the trigger would always occur at the same time). So T necessarily plays at least some role.

Looking at (C), we see a similar argument. We're told that some landfills charge by V, some by W and some by both. So differences in charges could be explained by V, W or both. Therefore, if there are different charges while holding V constant, then V can't fully explain the charges (otherwise they would be the same). So W must play at least some role.

I hope that helps!