Explanation: The Wildfires are considered very healthy when it comes to the forest. The wildfires helps in the eradication of the diseased and unhealthy plant and trees.
Though it is harmful for the animals living there in the forest but it is helpful for the trees there. It helps in the removal of insects causing disease and also helps in removal of the contaminated soil which helps in the growth of a healthy plant.
Not necessarily 'a' because saying the ecosystem would be healthier but then saying 'c' is true would be contradictory. I would say 'b' and 'c' are true but if you have to choose one then 'd' I guess
It would be weathered into sediments and then eroded and deposited and then pressure and heat would turn it into a sedimentary rock and then it would melt down into magma again and then it would cool into igneous after erupting again.
