What are stem cells, and why might a person with damage to the brain or spinal cord be very interested in the advancement of this field?

Stem Cells are defined as undifferentiated cells that can be used differentiate with other cell types within the body system, such as the brain and the spinal cord. People with brain and spinal cord damage are considered to look forward into this field, since stem cells hold the possibility of renewing and fixing tissues and relieve the brain or spinal cord from damage.

You did not show us the image of the burger, but i shall try to answer as best i can.  when purchasing food, always consider the ingredients as well as the person who prepared it. consider if they were hygienic people or not, in case the burger was infected with bacteria. no mortal should place an infected burger into their mouth.