Evaporation I think what school level is this ?
A species could gain negative traits through evolution. So, evolution does not always mean progress.
By elimination: d is wrong for sure.
c is not right as there is no gland in the esophagus or the pharynx
b is also wrong as if there is no gland, then there is no enzyme and no chemical digestion in <span>esophagus or pharynx
a is the only one left.</span>
Yes, it is B, because A population is
a sum of all the organisms of the same group or species.
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