The answer is; D
Radioactive waste poses a serious challenge to the environment. Any leakage of the waste is risky because the radioactivity can flow up the food chain and it also takes time for it to decay and become less harmful. Therefore, its effect can be felt over many generations. Therefore, safe storage of radioactive waste is a challenge (and can be very expensive) and a deterrent for pursuing the potent energy source.
Answer:
Sonic Hedgehog.
Explanation:
Sonic hedgehog is a secreted protein that in humans is encoded by the SHH gene. It is the best studied ligand of the hedgehog signaling pathway, others being desert hedgehog (DHH) and Indian hedgehog (IHH). It plays a key role in the development of animals, from insects to mammals. In vertebrates, it is involved in organogenesis, including the growth of digits on limbs and the organization of the brain.
Sonic hedgehog has also been shown to act as an axonal guidance cue. It has been demonstrated that SHH attracts commissural axons at the ventral midline of the developing spinal cord. Specifically, SHH attracts retinal ganglion cell (RGC) axons at low concentrations and repels them at higher concentrations
Plasma carries salts and enzymes, the primary purpose is to transport hormones, nutrients and proteins to part of the body that need it
