Which is not one of the layers in the soil profile?

the answer is:

in a biology class, the teacher started explaining a new lesson about the dna structure. personally, i found this lecture hard to understand. so i decided to use my critical thinking skills to be able to understand it. i analysed the different ideas, and broke them down into smaller parts to assimilate each. then i started evaluation and tried to link what i am learning with real life experiences so that i can make sure that i know how everything i am learning relates. finally, i started questioning by researching more what i learned and asking more questions that can me through my learning process. reflecting on the information meant that i should review it. all this me greatly understand what i previously found hard to understand.

hope it !