Cells Grown in a Petri Dish Tend to Divide Until

Multiple Choice

Cells grown in a petri dish tend to divide until they form a thin layer covering the bottom of the dish. If cells are removed from the middle of the dish, the cells bordering the open space will begin dividing until they have filled the empty space. What does this experiment show?

A) When cells come into contact with other cells, they stop growing.
B) The controls on cell growth and division can be turned on and off.
C) Cell division can be regulated by factors outside of the cell.
D) Cells continue to grow as long as there is adequate space.
E) All answers are valid and correct.