Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.

Seed plants which lived during the "carboniferous impact life" on Earth today because their "remains" formed "coal", which is an important resource.

Explanation:

During the Palaeozoic era, the carboniferous period lasted from "359 to 299 million years ago". The term carboniferous itself means rich deposits of coal. The swamp forests during that period produced coal. The climate was more uniform, tropical, humid. This is the result of the vast expansion of ocean covering the entire surface of Earth except few areas.  Many plants got buried in this period under swamps.

The answer is cultural