Which is a density-independent factor?
space
food sources
shelter
hurricanes

Density dependent factors are the aspects of the environment that limit a population's growth regardless of the density of the population. So in this case, the answer is hurricanes.

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.