技術が進歩してなにかが新しくできるようになると、それを _______ のです。
a) 使ってみたくてならない
b) 使ってみたくてたまらない
c) 使ってみたくてしょうがない
d) 使ってみたくて当然
The answer says that answer is b). According to my research てならない is used for feelings, and ようがない when something for some reason is impossible, but I have found translations as extremely.
Also read this post, but it seems the nuance would be different, but answers would still fit. Contrasting 〜てならない、〜てしょうがない and 〜てたまらない
IMHO, b) and c) are equally correct. Both ～したくてたまらない and ～したくてしょうがない refer to a strong and uncontrollable desire, which fits in this context well. The difference between them is small, but maybe ～したくてしょうがない sounds slightly more negative (i.e., may imply it's not considered good to do it). In this case, saying c) might have a slightly stronger implication that it's bad to prematurely use a new technology.
At least in modern Japanese, ～てならない is mainly used with adjectives and verbs that represent the speaker's own spontaneous feelings (e.g. ～という気がしてならない, 不思議でならない, 悲しくてならない), but ～たくてならない is simply uncommon. In BCCWJ, there are only two examples of ～たくてならない (and one example of ～たくてならぬ). But according to this article, 新潮文庫の100冊 (includes many older novels) has 11 examples of ～たくてならない, so it may have been more common in the past. I don't see any reason why 使ってみたくてならない is "incorrect", but I can say it's stiff and uncommon today.
当然 doesn't work because the sentence ends in のです. It would have to be 当然なのです to work. So you can already exclude 当然 from the possible answers.
All the others would indeed be grammatically correct, but usually these exercises ask you to choose the one answer that would fit the sentence the best.
Also you should think about the context, here without any further context, the one that's most likely to be used would be たまらない.
