The answers are A) ectoderm and B) endoderm.
Fertilization is a fusion of male and female gametes which leads to the formation of a zygote. The zygote undergoes mitosis and transforms into a single-layered blastula. Gastrulation is a transformation of the blastula into a two-layer or three-layer gastrula. Cnidarians are a diploblastic animal because their gastrula has only two layers - endoderm and ectoderm.
The correct answer is (a.) a mutation of the hemoglobin allowing better oxygen-carrying capacity. The mutation of the hemoglobin that allows a better oxygen-carrying capacity would be the most beneficial to an elephant and its descendants.
Alternative energy sources are those that do not deplete natural resources and do not harm the environment.
Options A, B, and C are all fossil fuels, which we know can be depleted and harm the environment.
The only valid option here is D, Geothermal energy.
Geothermal energy is both renewable and environmentally friendly.
