B. makes because google says so and i believe him
Typically, the background of a study includes a review of the existing literature on the area of your research, leading up to your topic. Once you have discussed the contribution of other researchers in the field, you can identify gaps in understanding, that is, areas that have not been addressed in these studies.
Not sure if this is what you meant, if not, let me know
Yes topaz is natural and formed and earth.
The greenhouse effect i think
D.temperate deciduous forest
