What technology can make coal a cleaner fuel? fluidized-bed combustion building smoke stacks taller implementing a prewash of coal prior to combustion using lower quality, high sulfur coal mixing coal with natural gas to create a hybrid fuel?

Answer : The technology that can make coal a cleaner fuel is to use lower quality of coal with high sulfur content.

Explanation : Using lower quality of coal with high amount of sulfur in it can make coal a cleaner fuel because of high amount of sulfur it will have better combustion.  

They did not study the continental drift

The correct answer is c b c a d