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
I believe the answer is Government subsidies. A subsidy is the form of cash payment or a tax reduction. It is normally given to remove some type of burden, and it is often considered to be in the overall interest of the public, given to promote a social good or economic policy. Tax subsidy; the government can create the same outcome through selective tax breaks as through cash payment. For example, suppose a government sends monetary assistance that reimburses 15% of all health expenditures to a group that is paying 15% income tax. Tax subsidies are also known as tax expenditures.
