@Arsham_Shafie I'm in the same boat. On a deeper look in BR, it almost felt obvious, but I immediately eliminated E on first read.

could D be right if it said that a majority of bladed etching tools ARE used for engraving?

I'm a bit confused, I learned in my science classes that an experiment to determine a causal relationship would also mean a relationship is valid. ie, if a study (under proper scrutiny) found a causal relationship that studying for the LSAT CAUSES a 10% increase in scores, then it is a valid conclusion that if study then increase in score. Am I misunderstanding or is LSAT causal different from scientific causal?

@joycetheok yeah, I was confused on that question as well.