Coal seams are far deep underground to be considered for opencast minings. These coal seams require underground mining. Since it is too deep underground, it can be used for mapping and correlation of sedimentary rocks or as a key bed.
The studies are designed this way b/c it removes the power of suggestion and the double-blind study keeps both researchers and participants in the dark. So this compared to who is receiving the treatment which is relevant b/c it stops the researchers from accidentally overbalancing the study participants, or unintentionally favoring their assessment of the conclusions.
Answer:
a
Explanation:
a lipid is the right answer
