Read the passage about stem cells.
Present in all kinds of tissues, stem cells have the unique ability to develop into other kinds of cells if necessary. An organism's stem cells can transform into brain cells, blood cells, muscle cells, or any other specialized cell found in the organism. Planarian worms have an extremely high stem cell count throughout their bodies.
Which answer best describes an advantage to a planarian worm from having a high stem cell count?
a
a planarian worm's cells can never truly die
b
planarian worms can adapt to any environmental changes
c
planarian worms are able to evolve faster than other organisms
d
a whole new planarian worm can grow from a tiny piece of another
d
a whole new planarian worm can grow from a tiny piece of another