Answer: Directional selection
Explanation:
In the population genetics, directional selection is the mode of selection during which the extreme phenotype are favored more than the other phenotype.
This causes the allele frequency to shift towards the time in the direction of that particular phenotype.
Here, in the question the acid tolerant plant species is favored over the other phenotype.
Hence, the correct answer is option D
It is much larger than the other ones
"A flower is called complete if all four floral organs are present in the same flower structure." ¬http://www.cropsreview.com/flower-types.html Awesome webpage on that.
