I agree that A, C, and D are correct.
In Q1 the two contenders are A and E. A is correct because what the first sentence wants to say about the "idea" is that it remained unchallenged until new research challenged it. This corresponds to answer choice A. Answer choice E represents the
content of the idea - the reduction of effort, but not the 'reception' of the idea - i.e. what was the attitude to this idea, how was it received by others? That is what the first sentence wants to tell us.
In Q2, C is correct - and the reasoning here closely parallels the reasoning above. The passage is about the challenge to a prevailing idea.
In Q3 - Notice the phrasing of the question - the researchers would agree that "modernizing house technology did NOT". It is easy to pick an incorrect answer choice by not paying attention to that final "NOT".
D is correct because the part of the passage that describes the analysis by Vanek and Cowan stresses that there were two different insights from the analysis. 1 - for particular tasks, the time spent on them was reduced. 2 - overall, in homes of full-time home workers, the total time spent on housework was not reduced. The correct answer choice refers to the latter insight. Answer choice B would only be correct without that final "NOT" in the question stem. C would only be correct in relation to insight no. 2, but not in relation to insight no. 1.