I believe this adaptation of the blue poppies to their environment is due to directional selection. Directional selection refers to the mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of the favored phenotype. In our case the plants with the thickest leaves were favored as they were more adaptable and in the end there was a shift to this characteristic by other plants.
Vertebrates have a bilateral symmetry due to which their entire body is divided into right and left halves while the invertebrates either have radial symmetry or the bilateral symmetry. Therefore, option D is correct.
The other basic differences between the vertebrates and the invertebrates are that vertebrates have a spinal cord and a backbone while invertebrates lack them, vertebrates have well developed brain, lungs or gills in respiratory system and closed circulatory system.
