[quote="tzec76"]I was thinking c is a better answer, but it is not.
Can anyone try, and then explain a better solution?
Although the genetic explanation of why some people
are right-handed, whereas others are left-handed
is plausible, it has been effectively __________
by experiments in which genetically ___________
mice showed different paw preferences.
mY money is choice B). Although suggests an apposing view later on here. The explanation has been effectively challenged by experiments. The argument is saying that it is genetics that plays the role of deciding left from right handed, but the although suggests that this is not true; mice with indistinguishable genes can be left or right handed (paw preferences).