Scientists rigorously studied a variety of possible causes, ranging from genetically modified crops to climate change to cell phone towers. How does the use of the word rigorously affect the tone of the excerpt?

What is the most important point that the authors make in this paragraph? most enslaved people worked under fair to good conditions. enslaved workers had decent lives if they had fair overseers. plantations often were harsh because of the cruelty of those in charge. men with absolute power can lose the sense of what it means to be good.