Answer:
a regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action.
Explanation:
Http://www.livescience.com/22537-skeletal-system.html
Pediculosis capitis, also known as hair lice, is one of the most common of ectoparasitic infections. This is highly contagious, especially in schools, day care centers, or areas wherein children are in close contact with infected children. In this case, the nurse should examine the heads of the children for small lice or nits on the hair shafts.
<span>The corpus callosum is what connects the left and right cerebral hemispheres of the brain. If it is severed, it would no longer be able to allow the two sides to communicate. In some cases, it is partially transected (severed) in patients that have severe epilepsy. The procedure is called a corpus callosotomy and is only done as a last resort.</span>
If you are implying one these choices not needed for survival it would be parents only when you can survive on your own (I'm not that sure but I hope this helped the slightest but)
