Answer: A. beaming
Explanation:
The best association for it would be the word 'Beaming' because we must include details from the sentence along with it.
There is talk about ''The caver'' and the ''treasure'' that is reflecting the light. That reflection of treasure is beaming because when it is 'beaming' it means that the object is glowing with the light. Since we are talking about the cavern, beaming light reflected from the treasure is eliminating the darkness from the cavern.
B) Collusion
Collusion is the act of two or more parties getting together to conspire or plan something secretly.
I guess it is important that your subject lines be worded correctly so as to avoid any confusion or misunderstanding. You want your audience (be that readers or listeners) to understand you correctly, and if you fail to word your ideas correctly, they won't be able to comprehend what it is you are trying to tell them.
It can make your paper more appealing to readers, and/or more informative for the readers as well.