There is no need to express opinions when we have good estimates for both your questions:

Sector by sector: where do global greenhouse gas emissions come from? -> https://ourworldindata.org/ghg-emissions-by-sector

individual solutions reviewed and assessed by Project Drawdown, including their relevant sector(s) and their impact on reducing heat-trapping gases -> https://drawdown.org/solutions/table-of-solutions

Both the links above are from a very interesting video on the topic that I suggest to take a look at. Also the whole channel is really interesting and well done -> https://www.youtube.com/watch?v=ReXaS4QausQ