<span>It is common for some toddlers to be very shy and not be sociable. This is due to the fact that they may not have any other siblings at home and do not get out much. The fact that other children play just fine is not alarming as everyone is different than others.</span>
The correct answer is option (a). Parent material
The soil horizon refers to distinct layers of the soils, which are parallel to one another, but have a different composition from the layer present above and below to it.
The soil horizon can be divided into four different layers. First one is organic layer, which is the topmost layer, below this layer second layer of topsoil is present. Below top soil, subsoil is present. Below subsoil, the bottom most horizon parent material is present.
A dependent variable is how they are recording, measuring or keeping track of the science experiment their doing.
A independent variable is the things/types there using to compare what is the most/least affective in the experiment.
A controlled variable is something that stays the same in the experiment or a group/set used for comparison
A) unproductive wastelands I believe is the answer you are looking for.
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Hope this helps...
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A user mentioned in the comments of one of the answers deleted: "its B" < The user (<span>lolbae0806) had mentioned this...</span>
So I believe the correct answer is:
B.) More oxygen gas became present in the atmosphere.