Why can’t the answer be ‘A’ here, given tempo generally refers to speed ?
The clause with tempo in it isn’t a complete idea, since there’s a blank in it. Do you see that the blank describes the tempo? The complete thought is the final clause. Do you see how that tells us what kind of tempo it is?
Edit: I understand what you mean. But tempo doesn’t mean speed. It refers to “how much speed”. It can be slow or fast, so tedious would only make sense if tempo always meant “fast”.
tedious means ‘slow’ or ‘dull’. I believe it fits well in regards to ‘how much speed’.
Where is the evidence of any slow tempo/speed here? As Vince stated above, tempo only means speed, it doesn’t mean slow.
What if the tempo was fast here?
that’s what tempted me to choose ‘tedious’ as answer. There is no option for fast speed, but one for slow speed.
Something with slow speed may or may not be boring. So tedious would never be right. But if one of the answer choices was “slow”, that would also never be right, because “tempo” may or may not be slow. We need evidence.
But you have to read the whole sentence. “without necessary relation to what had gone before” is key.